Clique-width: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
en>Headbomb
m References: Various citation cleanup and WP:AWB general fixes using AWB
 
en>Mark viking
Added wl
Line 1: Line 1:
det faktum att människor som lever med teknik finns det fortfarande några som är skeptiska till dessa justeringar . Dessa casino spelare som ifrågasätter om de kan använda riktiga pengar att spela mobil casino slots USA . World Wide Net är säker och webbplatser som använder kryptering för att skydda konfidentiell information såsom individ och konton .<br><br>Slumptals generationens metod är enligt en matematisk princip som heter sannolikhet. När mängden symboler ökar inom varje rulle , sedan många  nätcasino ([https://medium.com/@casino/ska-man-spela-pa-natcasino-4d116b99375d Read More Here]) fler kombinationer bildas . Detta system tenderar att göra positivt att kvantitetskombinationer är den samma för varje enskild spelare att spela spelet. Godheten om laptop genererade spel är sanningen att de kan garantera rättvisa eftersom mängden kontanter inte kan göra något för att justera resultatet av spelet . Det är bara tur som kan göra en spelare vinna i slots. Dator har inte möjlighet att kontrollera resultaten , eftersom det är bara programmerad att besluta om slumpmässiga symboler. Detta är förklaringen till varför slots är också känd som omgång möjlighet.<br><br>Att hantera kort är en talang som måste upptäckas behov av utbildade Casino Återförsäljare har aldrig varit större och Casino College På internet kan ge dig kanten du behöver och få dig att verka som ett kasino återförsäljare snabbare . Även om de flesta yrken kräver bokstavligen år av experiencebefore du kan även tycker om att söka jobbet , Dealing Poker & Blackjack är mycket tydlig . På grund av den extrema tillväxten i spelbranschen finns helt enkelt aren'tenough utbildade återförsäljare för att fylla alla positioner. Det finns otaliga Casino Dealer Lediga jobb bara väntar på att fyllas . Klicka här för att se en blygsam lista med Casino Lediga Jobb .<br><br>Med de många olika slots spel som erbjuds dig Jag får ofta frågan om vad online casino slot spel är perfekt lämpad för bonusar . De allra första förslag är att hålla sig borta från progressiva spel - de kanske låter lockande med sina mångmiljoneurojackpots , men eftersom de är anslutna till ett brett jackpotnätverk som spänner över många online-kasinon och har en lägre utdelningsandel jämfört med icke-progressiv spelautomater , det finns en betydligt större möjlighet att vinna när du spelar multiline slots med bonusspel - även om möjligheten att vinna en enorm jackpot är alltid mycket bättre rustade.<br><br>Vi går på rätt sätt längre än bara rapporterar nyheterna. Vi hålla på med nyheter och ibland blir vi även news.We stolta över att erbjuda följa upp täckning för enskilda nyheter stories.We hade reportrar inWashington DC på den ökända natten när banan spelförbudantogs av en nu visat sig vara korrupta , tidigare senator Bill Frist ledda kongressen , och vi havestaff ständigt gräva för att få kritiska uppgifter till amerikanska medborgare . Vi hade reportrar [http://www.dailymail.co.uk/home/search.html?sel=site&searchPhrase=p%C3%A5+Planet på Planet] Series of Poker i Las Vegas när Jamie Gold vann sin ring och ändrade på webben spelande planeten , och vi har representanter spelar [http://Www.Adobe.com/cfusion/search/index.cfm?term=&i+turneringen&loc=en_us&siteSection=home i turneringen] varje och varje år .
In the [[mathematics|mathematical]] theory of [[conformal mapping|conformal]] and [[quasiconformal mapping]]s, the '''extremal length''' of a collection of [[curve]]s <math>\Gamma</math> is a [[conformal invariant]] of <math>\Gamma</math>. More specifically, suppose that
<math>D</math> is an open set in the [[complex plane]] and <math>\Gamma</math> is a collection
of paths in <math>D</math> and <math>f:D\to D'</math> is a conformal mapping. Then the extremal length of <math>\Gamma</math> is equal to the extremal length of the image of <math>\Gamma</math> under <math> f</math>. For this reason, the extremal length is a useful tool in the study of conformal mappings. Extremal length can also be useful in dimensions greater than two,
but the following deals primarily with the two dimensional setting.
 
==Definition of extremal length==
To define extremal length, we need to first introduce several related quantities.
Let <math>D</math> be an open set in the complex plane. Suppose that <math>\Gamma</math> is a
collection of [[rectifiable curve]]s in <math>D</math>. If <math>\rho:D\to [0,\infty]</math>
is [[Borel algebra|Borel-measurable]], then for any rectifiable curve <math>\gamma</math> we let
 
:<math>L_\rho(\gamma):=\int_\gamma \rho\,|dz|</math>
 
denote the '''<math>\rho</math>-length of <math>\gamma</math>''', where <math>|dz|</math> denotes the
[[Euclidean distance|Euclidean]] element of length. (It is possible that <math>L_\rho(\gamma)=\infty</math>.)
What does this really mean?
If <math>\gamma:I\to D</math> is parameterized in some interval <math>I</math>,
then <math>\int_\gamma \rho\,|dz|</math> is the integral of the Borel-measurable function
<math>\rho(\gamma(t))</math> with respect to the Borel measure on <math>I</math>
for which the measure of every subinterval <math>J\subset I</math> is the length of the
restriction of <math>\gamma</math> to <math>J</math>. In other words, it is the
[[Lebesgue-Stieltjes integration|Lebesgue-Stieltjes integral]]
<math>\int_I \rho(\gamma(t))\,d{\mathrm{length}}_\gamma(t)</math>, where
<math>{\mathrm{length}}_\gamma(t)</math> is the length of the restriction of <math>\gamma</math>
to <math>\{s\in I:s\le t\}</math>.
Also set
 
:<math>L_\rho(\Gamma):=\inf_{\gamma\in\Gamma}L_\rho(\gamma).</math>
 
The '''area''' of <math>\rho</math> is defined as
:<math>A(\rho):=\int_D \rho^2\,dx\,dy,</math>
and the '''extremal length''' of <math>\Gamma</math> is
 
:<math>EL(\Gamma):= \sup_\rho \frac{L_\rho(\Gamma)^2}{A(\rho)}\,,</math>
 
where the supremum is over all Borel-measureable <math>\rho:D\to[0,\infty]</math> with <math>0<A(\rho)<\infty</math>. If <math>\Gamma</math> contains some non-rectifiable curves and
<math>\Gamma_0</math> denotes the set of rectifiable curves in <math>\Gamma</math>, then
<math>EL(\Gamma)</math> is defined to be <math>EL(\Gamma_0)</math>.
 
The term '''modulus''' of <math>\Gamma</math> refers to <math>1/EL(\Gamma)</math>.
 
The '''extremal distance''' in <math>D</math> between two sets in <math>\overline D</math> is the extremal length of the collection of curves in <math>D</math> with one endpoint in one set and the other endpoint in the other set.
 
==Examples==
 
In this section the extremal length is calculated in several examples. The first three of these examples are actually useful in applications of extremal length.
 
===Extremal distance in rectangle===
Fix some positive numbers <math>w,h>0</math>, and let <math>R</math> be the rectangle
<math>R=(0,w)\times(0,h)</math>. Let <math>\Gamma</math> be the set of all finite
length curves <math>\gamma:(0,1)\to R</math> that cross the rectangle left to right,
in the sense that <math>\lim_{t\to 0}\gamma(t)</math>
is on the left edge <math>\{0\}\times[0,h]</math> of the rectangle, and
<math>\lim_{t\to 1}\gamma(t)</math> is on the right edge <math>\{1\}\times[0,h]</math>.
(The limits necessarily exist, because we are assuming that <math>\gamma</math>
has finite length.) We will now prove that in this case
:<math>EL(\Gamma)=w/h</math>
 
First, we may take <math>\rho=1</math> on <math>R</math>. This <math>\rho</math>
gives <math>A(\rho)=w\,h</math> and <math>L_\rho(\Gamma)=w</math>. The definition
of <math>EL(\Gamma)</math> as a supremum then gives <math>EL(\Gamma)\ge w/h</math>.
 
The opposite inequality is not quite so easy. Consider an arbitrary
Borel-measurable <math>\rho:R\to[0,\infty]</math> such that
<math>\ell:=L_\rho(\Gamma)>0</math>.
For <math>y\in(0,h)</math>, let <math>\gamma_y(t)=i\,y+w\,t</math>
(where we are identifying <math>\R^2</math> with the complex plane).
Then <math>\gamma_y\in\Gamma</math>, and hence <math>\ell\le L_\rho(\gamma_y)</math>.
The latter inequality may be written as
:<math> \ell\le \int_0^1 \rho(i\,y+w\,t)\,w\,dt .</math>
Integrating this inequality over <math>y\in(0,h)</math> implies
:<math> h\,\ell\le \int_0^h\int_0^1\rho(i\,y+w\,t)\,w\,dt\,dy</math>.
Now a change of variable <math>x=w\,t</math> and an application of the [[Cauchy-Schwarz inequality]] give
:<math> h\,\ell \le \int_0^h\int_0^w\rho(x+i\,y)\,dx\,dy \le \Bigl(\int_R \rho^2\,dx\,dy\int_R\,dx\,dy\Bigr)^{1/2} = \bigl(w\,h\,A(\rho)\bigr)^{1/2}</math>. This gives <math>\ell^2/A(\rho)\le w/h</math>.
Therefore, <math>EL(\Gamma)\le w/h</math>, as required.
 
As the proof shows, the extremal length of <math>\Gamma</math> is the same as the extremal
length of the much smaller collection of curves <math>\{\gamma_y:y\in(0,h)\}</math>.
 
It should be pointed out that the extremal length of the family of curves <math>\Gamma\,'</math>
that connect the bottom edge of <math> R</math> to the top edge of <math>R</math> satisfies
<math>EL(\Gamma\,')=h/w</math>, by the same argument. Therefore, <math>EL(\Gamma)\,EL(\Gamma\,')=1</math>.
It is natural to refer to this as a duality property of extremal length, and a similar duality property
occurs in the context of the next subsection. Observe that obtaining a lower bound on
<math>EL(\Gamma)</math> is generally easier than obtaining an upper bound, since the lower bound involves
choosing a reasonably good <math>\rho</math> and estimating <math>L_\rho(\Gamma)^2/A(\rho)</math>,
while the upper bound involves proving a statement about all possible <math>\rho</math>. For this reason,
duality is often useful when it can be established: when we know that <math>EL(\Gamma)\,EL(\Gamma\,')=1</math>,
a lower bound on <math>EL(\Gamma\,')</math> translates to an upper bound on <math>EL(\Gamma)</math>.
 
===Extremal distance in annulus===
Let <math>r_1</math> and <math>r_2</math> be two radii satisfying
<math> 0<r_1<r_2<\infty</math>. Let <math>A</math> be the
annulus <math>A:=\{z\in\mathbb C:r_1<|z|<r_2\}</math> and let
<math>C_1</math> and <math>C_2</math> be the two boundary components
of <math>A</math>: <math>C_1:=\{z:|z|=r_1\}</math>
and <math>C_2:=\{z:|z|=r_2\}</math>. Consider the extremal distance
in <math>A</math> between <math>C_1</math> and <math>C_2</math>;
which is the extremal length of the collection <math>\Gamma</math> of
curves <math>\gamma\subset A</math> connecting <math>C_1</math>
and <math>C_2</math>.  
 
To obtain a lower bound on <math>EL(\Gamma)</math>,
we take <math>\rho(z)=1/|z|</math>. Then for <math>\gamma\in\Gamma</math>
oriented from <math>C_1</math> to <math>C_2</math>
:<math>\int_\gamma |z|^{-1}\,ds \ge \int_\gamma |z|^{-1}\,d|z| = \int_\gamma d\log |z|=\log(r_2/r_1).</math>
On the other hand,
:<math>A(\rho)=\int_A |z|^{-2}\,dx\,dy= \int_{0}^{2\pi}\int_{r_1}^{r_2} r^{-2}\,r\,dr\,d\theta = 2\,\pi \,\log(r_2/r_1).</math>
We conclude that
:<math>EL(\Gamma)\ge \frac{\log(r_2/r_1)}{2\pi}.</math>
 
We now see that this inequality is really an equality by employing an argument similar to the one given above for the rectangle. Consider an arbitrary Borel-measurable <math>\rho</math> such that <math>\ell:=L_\rho(\Gamma)>0</math>. For <math>\theta\in[0,2\,\pi)</math> let <math>\gamma_\theta:(r_1,r_2)\to A</math> denote the curve <math>\gamma_\theta(r)=e^{i\theta}r</math>. Then
:<math>\ell\le\int_{\gamma_\theta}\rho\,ds =\int_{r_1}^{r_2}\rho(e^{i\theta}r)\,dr.</math>
We integrate over <math>\theta</math> and apply the Cauchy-Schwarz inequality, to obtain:
:<math>2\,\pi\,\ell \le \int_A \rho\,dr\,d\theta \le \Bigl(\int_A \rho^2\,r\,dr\,d\theta \Bigr)^{1/2}\Bigl(\int_0^{2\pi}\int_{r_1}^{r_2} \frac 1 r\,dr\,d\theta\Bigr)^{1/2}.</math>
Squaring gives
:<math>4\,\pi^2\,\ell^2\le A(\rho)\cdot\,2\,\pi\,\log(r_2/r_1).</math>
This implies the upper bound <math>EL(\Gamma)\le (2\,\pi)^{-1}\,\log(r_2/r_1)</math>.
When combined with the lower bound, this yields the exact value of the extremal length:
:<math>EL(\Gamma)=\frac{\log(r_2/r_1)}{2\pi}.</math>
 
===Extremal length around an annulus===
Let <math>r_1,r_2,C_1,C_2,\Gamma</math> and <math>A</math> be as above, but now let <math>\Gamma^*</math> be the collection of all curves that wind once around the annulus, separating <math>C_1</math> from <math>C_2</math>. Using the above methods, it is not hard to show that
:<math>EL(\Gamma^*)=\frac{2\pi}{\log(r_2/r_1)}=EL(\Gamma)^{-1}.</math>
This illustrates another instance of extremal length duality.
 
===Extremal length of topologically essential paths in projective plane===
In the above examples, the extremal <math>\rho</math> which maximized the
ratio <math>L_\rho(\Gamma)^2/A(\rho)</math> and gave the extremal length corresponded to a flat metric. In other words, when the [[Euclidean distance|Euclidean]] [[Riemannian metric]] of the corresponding planar domain is scaled by <math>\rho</math>, the resulting metric is flat. In the case of the rectangle, this was just the original metric, but for the annulus, the extremal metric identified is the metric of a [[cylinder (geometry)|cylinder]]. We now discuss an example where an extremal metric is not flat. The projective plane with the spherical metric is obtained by identifying [[antipodal point]]s on the unit sphere in <math>\R^3</math> with its Riemannian spherical metric. In other words, this is the quotient of the sphere by the map <math>x\mapsto -x</math>. Let <math>\Gamma</math> denote the set of closed curves in this projective plane that are not [[null-homotopic]]. (Each curve in <math>\Gamma</math> is obtained by projecting a curve on the sphere from a point to its antipode.) Then the spherical metric is extremal for this curve family.<ref>Ahlfors (1973)</ref> (The definition of extremal length readily extends to Riemannian surfaces.) Thus, the extremal length is <math>\pi^2/(2\,\pi)=\pi/2</math>.
 
===Extremal length of paths containing a point===
If <math>\Gamma</math> is any collection of paths all of which have positive diameter and containing a point <math>z_0</math>, then <math>EL(\Gamma)=\infty</math>. This follows, for example, by taking
:<math>\rho(z):= \begin{cases}(-|z-z_0|\,\log |z-z_0|)^{-1} & |z-z_0|<1/2,\\
0 & |z-z_0|\ge 1/2,\end{cases}</math>
which satisfies <math>A(\rho)<\infty</math> and <math>L_\rho(\gamma)=\infty</math> for every rectifiable <math>\gamma\in\Gamma</math>.
 
==Elementary properties of extremal length==
The extremal length satisfies a few simple monotonicity properties. First, it is clear that if <math>\Gamma_1\subset\Gamma_2</math>, then <math>EL(\Gamma_1)\ge EL(\Gamma_2)</math>.
Moreover, the same conclusion holds if every curve <math>\gamma_1\in\Gamma_1</math> contains a curve <math>\gamma_2\in \Gamma_2</math> as a subcurve (that is, <math>\gamma_2</math> is the restriction of <math>\gamma_1</math> to a subinterval of its domain). Another sometimes useful inequality is
:<math>EL(\Gamma_1\cup\Gamma_2)\ge \bigl(EL(\Gamma_1)^{-1}+EL(\Gamma_2)^{-1}\bigr)^{-1}.</math>
This is clear if <math>EL(\Gamma_1)=0</math> or if <math>EL(\Gamma_2)=0</math>, in which case the right hand side is interpreted as <math>0</math>. So suppose that this is not the case and with no loss of generality assume that the curves in <math>\Gamma_1\cup\Gamma_2</math> are all rectifiable. Let <math>\rho_1,\rho_2</math> satisfy <math>L_{\rho_j}(\Gamma_j)\ge 1</math> for <math>j=1,2</math>. Set <math>\rho=\max\{\rho_1,\rho_2\}</math>. Then <math>L_\rho(\Gamma_1\cup\Gamma_2)\ge 1</math> and <math>A(\rho)=\int\rho^2\,dx\,dy\le\int(\rho_1^2+\rho_2^2)\,dx\,dy=A(\rho_1)+A(\rho_2)</math>, which proves the inequality.
 
==Conformal invariance of extremal length==
Let <math>f:D\to D^*</math> be a [[conformal map|conformal]] [[homeomorphism]]
(a [[bijective]] [[holomorphic]] map) between planar domains. Suppose that
<math>\Gamma</math> is a collection of curves in <math>D</math>,
and let <math>\Gamma^*:=\{f\circ \gamma:\gamma\in\Gamma\}</math> denote the
image curves under <math>f</math>. Then <math>EL(\Gamma)=EL(\Gamma^*)</math>.
This conformal invariance statement is the primary reason why the concept of
extremal length is useful.
 
Here is a proof of conformal invariance. Let <math>\Gamma_0</math> denote the set of curves
<math>\gamma\in\Gamma</math> such that <math>f\circ \gamma</math> is rectifiable, and let
<math>\Gamma_0^*=\{f\circ\gamma:\gamma\in\Gamma_0\}</math>, which is the set of rectifiable
curves in <math>\Gamma^*</math>. Suppose that <math>\rho^*:D^*\to[0,\infty]</math> is Borel-measurable. Define
:<math>\rho(z)=|f\,'(z)|\,\rho^*\bigl(f(z)\bigr).</math>
A [[change of variable]]s <math>w=f(z)</math> gives
:<math>A(\rho)=\int_D \rho(z)^2\,dz\,d\bar z=\int_D \rho^*(f(z))^2\,|f\,'(z)|^2\,dz\,d\bar z = \int_{D^*} \rho^*(w)^2\,dw\,d\bar w=A(\rho^*).</math>
Now suppose that <math>\gamma\in \Gamma_0</math> is rectifiable, and set <math>\gamma^*:=f\circ\gamma</math>. Formally, we may use a change of variables again:
:<math>L_\rho(\gamma)=\int_\gamma \rho^*\bigl(f(z)\bigr)\,|f\,'(z)|\,|dz| = \int_{\gamma^*} \rho(w)\,|dw|=L_{\rho^*}(\gamma^*).</math>
To justify this formal calculation, suppose that <math>\gamma</math> is defined in some interval <math>I</math>, let
<math>\ell(t)</math> denote the length of the restriction of <math>\gamma</math> to <math>I\cap(-\infty,t]</math>,
and let <math>\ell^*(t)</math> be similarly defined with <math>\gamma^*</math> in place of <math>\gamma</math>. Then it is easy to see that <math>d\ell^*(t)=|f\,'(\gamma(t))|\,d\ell(t)</math>, and this implies <math>L_\rho(\gamma)=L_{\rho^*}(\gamma^*)</math>, as required. The above equalities give,
:<math>EL(\Gamma_0)\ge EL(\Gamma_0^*)=EL(\Gamma^*).</math>
If we knew that each curve in <math>\Gamma</math> and <math>\Gamma^*</math> was rectifiable, this would
prove <math>EL(\Gamma)=EL(\Gamma^*)</math> since we may also apply the above with <math>f</math> replaced by its inverse
and <math>\Gamma</math> interchanged with <math>\Gamma^*</math>. It remains to handle the non-rectifiable curves.
 
Now let <math>\hat\Gamma</math> denote the set of rectifiable curves <math>\gamma\in\Gamma</math> such that <math>f\circ\gamma</math> is
non-rectifiable. We claim that <math>EL(\hat\Gamma)=\infty</math>.
Indeed, take <math>\rho(z)=|f\,'(z)|\,h(|f(z)|)</math>, where <math>h(r)=\bigl(r\,\log (r+2)\bigr)^{-1}</math>.
Then a change of variable as above gives
:<math>A(\rho)= \int_{D^*} h(|w|)^2\,dw\,d\bar w \le \int_0^{2\pi}\int_0^\infty (r\,\log (r+2))^{-2} \,r\,dr\,d\theta<\infty.</math>
For <math>\gamma\in\hat\Gamma</math> and <math>r\in(0,\infty)</math> such that <math>f\circ \gamma</math>
is contained in <math>\{z:|z|<r\}</math>, we have
:<math>L_\rho(\gamma)\ge\inf\{h(s):s\in[0,r]\}\,\mathrm{length}(f\circ\gamma)=\infty</math>.{{Dubious|date=November 2008}}
On the other hand, suppose that <math>\gamma\in\hat\Gamma</math> is such that <math>f\circ\gamma</math> is unbounded.
Set <math>H(t):=\int_0^t h(s)\,ds</math>. Then
<math>L_\rho(\gamma)</math> is at least the length of the curve <math>t\mapsto H(|f\circ \gamma(t)|)</math>
(from an interval in <math>\R</math> to <math>\R</math>). Since <math>\lim_{t\to\infty}H(t)=\infty</math>,
it follows that <math>L_\rho(\gamma)=\infty</math>.
Thus, indeed, <math>EL(\hat\Gamma)=\infty</math>.
 
Using the results of the [[#Elementary properties of extremal length|previous section]], we have
:<math>EL(\Gamma)=EL(\Gamma_0\cup\hat\Gamma)\ge EL(\Gamma_0)</math>.
We have already seen that <math>EL(\Gamma_0)\ge EL(\Gamma^*)</math>. Thus, <math>EL(\Gamma)\ge EL(\Gamma^*)</math>.
The reverse inequality holds by symmetry, and conformal invariance is therefore established.
 
==Some applications of extremal length== <!-- Reimann mapping theorem links here -->
By the [[#Extremal distance in annulus|calculation]] of the extremal distance in an annulus and the conformal
invariance it follows that the annulus <math>\{z:r<|z|<R\}</math> (where <math>0\le r<R\le\infty</math>)
is not conformally homeomorphic to the annulus <math>\{w:r^*<|w|<R^*\}</math> if <math>\frac Rr\ne \frac{R^*}{r^*}</math>.
 
==Extremal length in higher dimensions==
The notion of extremal length adapts to the study of various problems in dimensions 3 and higher, especially in relation to [[quasiconformal]] mappings.  
{{Expand section|date=June 2008}}
 
==Discrete extremal length==
Suppose that <math>G=(V,E)</math> is some [[graph (mathematics)|graph]] and <math>\Gamma</math> is a collection of paths in <math>G</math>. There are two variants of extremal length in this setting. To define the '''edge extremal length''', originally introduced by [[R. J. Duffin]],<ref>Duffin 1962</ref> consider a function <math>\rho:E\to[0,\infty)</math>. The <math>\rho</math>-length of a path is defined as the sum of <math>\rho(e)</math> over all edges in the path, counted with multiplicity. The "'''area'''" <math>A(\rho)</math> is defined as <math>\sum_{e\in E}\rho(e)^2</math>. The extremal length of <math>\Gamma</math> is then defined as before. If <math>G</math> is interpreted as a [[resistor network]], where each edge has unit resistance, then the [[effective resistance]] between two sets of veritces is precisely the edge extremal length of the collection of paths with one endpoint in one set and the other endpoint in the other set. Thus, discrete extremal length is useful for estimates in discrete [[potential theory]].
 
Another notion of discrete extremal length that is appropriate in other contexts is '''vertex extremal length''', where <math>\rho:V\to[0,\infty)</math>, the area is <math>A(\rho):=\sum_{v\in V}\rho(v)^2</math>, and the length of a path is the sum of <math>\rho(v)</math> over the vertices visited by the path, with multiplicity.
 
==Notes==
{{reflist|2}}
 
==References==
*{{Citation | author1-link=Lars Ahlfors | last1=Ahlfors | first1=Lars V. | title=Conformal invariants: topics in geometric function theory | publisher=McGraw-Hill Book Co. | location=New York | mr=0357743 | year=1973}}
*{{Citation | last1=Duffin | first1=R. J. | title= The extremal length of a network | year=1962 | journal=Journal of Mathematical Analysis and Applications | volume=5 | pages=200–215 | doi=10.1016/S0022-247X(62)80004-3 | issue=2}}
*{{Citation | last1=Lehto | first1=O. | last2=Virtanen | first2=K. I. | title=Quasiconformal mappings in the plane | publisher=[[Springer-Verlag]] | location=Berlin, New York | edition=2nd | year=1973}}
 
{{DEFAULTSORT:Extremal Length}}
[[Category:Conformal mapping]]
[[Category:Potential theory]]

Revision as of 05:32, 9 October 2013

In the mathematical theory of conformal and quasiconformal mappings, the extremal length of a collection of curves Γ is a conformal invariant of Γ. More specifically, suppose that D is an open set in the complex plane and Γ is a collection of paths in D and f:DD is a conformal mapping. Then the extremal length of Γ is equal to the extremal length of the image of Γ under f. For this reason, the extremal length is a useful tool in the study of conformal mappings. Extremal length can also be useful in dimensions greater than two, but the following deals primarily with the two dimensional setting.

Definition of extremal length

To define extremal length, we need to first introduce several related quantities. Let D be an open set in the complex plane. Suppose that Γ is a collection of rectifiable curves in D. If ρ:D[0,] is Borel-measurable, then for any rectifiable curve γ we let

Lρ(γ):=γρ|dz|

denote the ρ-length of γ, where |dz| denotes the Euclidean element of length. (It is possible that Lρ(γ)=.) What does this really mean? If γ:ID is parameterized in some interval I, then γρ|dz| is the integral of the Borel-measurable function ρ(γ(t)) with respect to the Borel measure on I for which the measure of every subinterval JI is the length of the restriction of γ to J. In other words, it is the Lebesgue-Stieltjes integral Iρ(γ(t))dlengthγ(t), where lengthγ(t) is the length of the restriction of γ to {sI:st}. Also set

Lρ(Γ):=infγΓLρ(γ).

The area of ρ is defined as

A(ρ):=Dρ2dxdy,

and the extremal length of Γ is

EL(Γ):=supρLρ(Γ)2A(ρ),

where the supremum is over all Borel-measureable ρ:D[0,] with 0<A(ρ)<. If Γ contains some non-rectifiable curves and Γ0 denotes the set of rectifiable curves in Γ, then EL(Γ) is defined to be EL(Γ0).

The term modulus of Γ refers to 1/EL(Γ).

The extremal distance in D between two sets in D is the extremal length of the collection of curves in D with one endpoint in one set and the other endpoint in the other set.

Examples

In this section the extremal length is calculated in several examples. The first three of these examples are actually useful in applications of extremal length.

Extremal distance in rectangle

Fix some positive numbers w,h>0, and let R be the rectangle R=(0,w)×(0,h). Let Γ be the set of all finite length curves γ:(0,1)R that cross the rectangle left to right, in the sense that limt0γ(t) is on the left edge {0}×[0,h] of the rectangle, and limt1γ(t) is on the right edge {1}×[0,h]. (The limits necessarily exist, because we are assuming that γ has finite length.) We will now prove that in this case

EL(Γ)=w/h

First, we may take ρ=1 on R. This ρ gives A(ρ)=wh and Lρ(Γ)=w. The definition of EL(Γ) as a supremum then gives EL(Γ)w/h.

The opposite inequality is not quite so easy. Consider an arbitrary Borel-measurable ρ:R[0,] such that :=Lρ(Γ)>0. For y(0,h), let γy(t)=iy+wt (where we are identifying 2 with the complex plane). Then γyΓ, and hence Lρ(γy). The latter inequality may be written as

01ρ(iy+wt)wdt.

Integrating this inequality over y(0,h) implies

h0h01ρ(iy+wt)wdtdy.

Now a change of variable x=wt and an application of the Cauchy-Schwarz inequality give

h0h0wρ(x+iy)dxdy(Rρ2dxdyRdxdy)1/2=(whA(ρ))1/2. This gives 2/A(ρ)w/h.

Therefore, EL(Γ)w/h, as required.

As the proof shows, the extremal length of Γ is the same as the extremal length of the much smaller collection of curves {γy:y(0,h)}.

It should be pointed out that the extremal length of the family of curves Γ that connect the bottom edge of R to the top edge of R satisfies EL(Γ)=h/w, by the same argument. Therefore, EL(Γ)EL(Γ)=1. It is natural to refer to this as a duality property of extremal length, and a similar duality property occurs in the context of the next subsection. Observe that obtaining a lower bound on EL(Γ) is generally easier than obtaining an upper bound, since the lower bound involves choosing a reasonably good ρ and estimating Lρ(Γ)2/A(ρ), while the upper bound involves proving a statement about all possible ρ. For this reason, duality is often useful when it can be established: when we know that EL(Γ)EL(Γ)=1, a lower bound on EL(Γ) translates to an upper bound on EL(Γ).

Extremal distance in annulus

Let r1 and r2 be two radii satisfying 0<r1<r2<. Let A be the annulus A:={z:r1<|z|<r2} and let C1 and C2 be the two boundary components of A: C1:={z:|z|=r1} and C2:={z:|z|=r2}. Consider the extremal distance in A between C1 and C2; which is the extremal length of the collection Γ of curves γA connecting C1 and C2.

To obtain a lower bound on EL(Γ), we take ρ(z)=1/|z|. Then for γΓ oriented from C1 to C2

γ|z|1dsγ|z|1d|z|=γdlog|z|=log(r2/r1).

On the other hand,

A(ρ)=A|z|2dxdy=02πr1r2r2rdrdθ=2πlog(r2/r1).

We conclude that

EL(Γ)log(r2/r1)2π.

We now see that this inequality is really an equality by employing an argument similar to the one given above for the rectangle. Consider an arbitrary Borel-measurable ρ such that :=Lρ(Γ)>0. For θ[0,2π) let γθ:(r1,r2)A denote the curve γθ(r)=eiθr. Then

γθρds=r1r2ρ(eiθr)dr.

We integrate over θ and apply the Cauchy-Schwarz inequality, to obtain:

2πAρdrdθ(Aρ2rdrdθ)1/2(02πr1r21rdrdθ)1/2.

Squaring gives

4π22A(ρ)2πlog(r2/r1).

This implies the upper bound EL(Γ)(2π)1log(r2/r1). When combined with the lower bound, this yields the exact value of the extremal length:

EL(Γ)=log(r2/r1)2π.

Extremal length around an annulus

Let r1,r2,C1,C2,Γ and A be as above, but now let Γ* be the collection of all curves that wind once around the annulus, separating C1 from C2. Using the above methods, it is not hard to show that

EL(Γ*)=2πlog(r2/r1)=EL(Γ)1.

This illustrates another instance of extremal length duality.

Extremal length of topologically essential paths in projective plane

In the above examples, the extremal ρ which maximized the ratio Lρ(Γ)2/A(ρ) and gave the extremal length corresponded to a flat metric. In other words, when the Euclidean Riemannian metric of the corresponding planar domain is scaled by ρ, the resulting metric is flat. In the case of the rectangle, this was just the original metric, but for the annulus, the extremal metric identified is the metric of a cylinder. We now discuss an example where an extremal metric is not flat. The projective plane with the spherical metric is obtained by identifying antipodal points on the unit sphere in 3 with its Riemannian spherical metric. In other words, this is the quotient of the sphere by the map xx. Let Γ denote the set of closed curves in this projective plane that are not null-homotopic. (Each curve in Γ is obtained by projecting a curve on the sphere from a point to its antipode.) Then the spherical metric is extremal for this curve family.[1] (The definition of extremal length readily extends to Riemannian surfaces.) Thus, the extremal length is π2/(2π)=π/2.

Extremal length of paths containing a point

If Γ is any collection of paths all of which have positive diameter and containing a point z0, then EL(Γ)=. This follows, for example, by taking

ρ(z):={(|zz0|log|zz0|)1|zz0|<1/2,0|zz0|1/2,

which satisfies A(ρ)< and Lρ(γ)= for every rectifiable γΓ.

Elementary properties of extremal length

The extremal length satisfies a few simple monotonicity properties. First, it is clear that if Γ1Γ2, then EL(Γ1)EL(Γ2). Moreover, the same conclusion holds if every curve γ1Γ1 contains a curve γ2Γ2 as a subcurve (that is, γ2 is the restriction of γ1 to a subinterval of its domain). Another sometimes useful inequality is

EL(Γ1Γ2)(EL(Γ1)1+EL(Γ2)1)1.

This is clear if EL(Γ1)=0 or if EL(Γ2)=0, in which case the right hand side is interpreted as 0. So suppose that this is not the case and with no loss of generality assume that the curves in Γ1Γ2 are all rectifiable. Let ρ1,ρ2 satisfy Lρj(Γj)1 for j=1,2. Set ρ=max{ρ1,ρ2}. Then Lρ(Γ1Γ2)1 and A(ρ)=ρ2dxdy(ρ12+ρ22)dxdy=A(ρ1)+A(ρ2), which proves the inequality.

Conformal invariance of extremal length

Let f:DD* be a conformal homeomorphism (a bijective holomorphic map) between planar domains. Suppose that Γ is a collection of curves in D, and let Γ*:={fγ:γΓ} denote the image curves under f. Then EL(Γ)=EL(Γ*). This conformal invariance statement is the primary reason why the concept of extremal length is useful.

Here is a proof of conformal invariance. Let Γ0 denote the set of curves γΓ such that fγ is rectifiable, and let Γ0*={fγ:γΓ0}, which is the set of rectifiable curves in Γ*. Suppose that ρ*:D*[0,] is Borel-measurable. Define

ρ(z)=|f(z)|ρ*(f(z)).

A change of variables w=f(z) gives

A(ρ)=Dρ(z)2dzdz¯=Dρ*(f(z))2|f(z)|2dzdz¯=D*ρ*(w)2dwdw¯=A(ρ*).

Now suppose that γΓ0 is rectifiable, and set γ*:=fγ. Formally, we may use a change of variables again:

Lρ(γ)=γρ*(f(z))|f(z)||dz|=γ*ρ(w)|dw|=Lρ*(γ*).

To justify this formal calculation, suppose that γ is defined in some interval I, let (t) denote the length of the restriction of γ to I(,t], and let *(t) be similarly defined with γ* in place of γ. Then it is easy to see that d*(t)=|f(γ(t))|d(t), and this implies Lρ(γ)=Lρ*(γ*), as required. The above equalities give,

EL(Γ0)EL(Γ0*)=EL(Γ*).

If we knew that each curve in Γ and Γ* was rectifiable, this would prove EL(Γ)=EL(Γ*) since we may also apply the above with f replaced by its inverse and Γ interchanged with Γ*. It remains to handle the non-rectifiable curves.

Now let Γ^ denote the set of rectifiable curves γΓ such that fγ is non-rectifiable. We claim that EL(Γ^)=. Indeed, take ρ(z)=|f(z)|h(|f(z)|), where h(r)=(rlog(r+2))1. Then a change of variable as above gives

A(ρ)=D*h(|w|)2dwdw¯02π0(rlog(r+2))2rdrdθ<.

For γΓ^ and r(0,) such that fγ is contained in {z:|z|<r}, we have

Lρ(γ)inf{h(s):s[0,r]}length(fγ)=.To succeed in selling a home, it is advisable be competent in real estate advertising and marketing, authorized, monetary, operational aspects, and other information and skills. This is essential as a result of you want to negotiate with more and more sophisticated buyers. You could outperform rivals, use latest technologies, and stay ahead of the fast altering market.

Home is where the center is, and choosing the right house is a part of guaranteeing a contented expertise in Singapore. Most expats sign up for a two-year lease with the option to resume, so it is value taking the time to choose a neighbourhood that has the services you want. The experts at Expat Realtor have compiled the next data that will help you negotiate your means by way of the property minefield. Some government state properties for rent. Over 2000 units available for lease however occupancy is often excessive. Some properties come under a bidding system. Their property brokers embody DTZ and United Premas. Up to date serviced residences located just off Orchard Highway. one hundred sixty Orchard Highway, #06-01 Orchard Level, Singapore 238842. Institute Of Property Agents

There is no such thing as a deal too small. Property agents who're willing to find time for any deal even when the commission is small are those you want in your side. They also show humbleness and might relate with the average Singaporean higher. Relentlessly pursuing any deal, calling prospects even without being prompted. Even when they get rejected a hundred times, they still come back for more. These are the property brokers who will find consumers what they want finally, and who would be the most profitable in what they do. four. Honesty and Integrity

As a realtor, you're our own business. Due to this fact, it is imperative that you handle yours prices and spend money correctly in order to market your property successfully. Also, beware of mentors who always ask you to pay for pointless costs. Such mentors typically are recruiting to develop a staff and see you as a option to defray advertising and marketing prices. For foreigners who want to register with CEA as salespersons, they might want to have a valid Employment Cross (EP) issued by the Ministry of Manpower (MOM). They should consult an property agent that is ready to assist their future registration software, who would then examine with CEA. Thereafter, after they register for the RES Course, they might want to produce a letter of assist from the property agent."

Main Real Property Brokers with in depth local knowledge, Carole Ann, Elizabeth and their group of extremely skilled property consultants provide a personalised service, for those looking to buy, lease or promote in Singapore. Relocation companies out there. Properties for the aesthete. Boutique real property agency for architecturally distinguished, unique properties for rent and on the market. Caters to the niche market of design-savvy people. Sale, letting and property management and taxation services. three Shenton Means, #10-08 Shenton Home, Singapore 068805. Buy property, promote or leasing estate company. 430 Lorong 6 Toa Payoh, #08-01 OrangeTee Constructing, Singapore 319402. HIGH Date / Age of property Estate Agents and Home Search Services Property Information Highlights Prime Achievers

From the above info, you may see that saving on agent's commission will not cover the expenses wanted to market your home efficiently. As well as, it's essential make investments a whole lot of time, vitality and effort. By taking yourself away from your work and other endeavors, additionally, you will incur unnecessary opportunity prices. There may be additionally no assurance you could beat the market and get the outcomes you need. That is why you want an agent - not simply an ordinary agent - you want knowledgeable and competent specialist, geared up with the best instruments and knowledge to serve you and lead you to success! Within the midst of this ‘uniquely Singapore' Property GSS, our most needed foreign customers are nowhere to be seen. Different types of Public Residential properties

Based on Kelvin, other agents may also make use of your agent's listings. "If your pricing is on the excessive aspect, these brokers may use your house to persuade their patrons why Http://Trafficstooges.Com/Singapore-Property-Condominium they should purchase another residence." To counter this, Kelvin says it is crucial for your agent to supply a current market analysis before putting up your private home for sale. "This helps you worth your property appropriately and realistically." When property is made accessible (HIGH is issued) to the client. Becoming a successful property agent is a distinct story altogether! Hi, I would like to ask how I might be a property agent and whether there are courses I might take. And if I need to be at a certain age. www. Property BUYER com.sg (your impartial Mortgage Advisor) In private properties in

On the other hand, suppose that γΓ^ is such that fγ is unbounded. Set H(t):=0th(s)ds. Then Lρ(γ) is at least the length of the curve tH(|fγ(t)|) (from an interval in to ). Since limtH(t)=, it follows that Lρ(γ)=. Thus, indeed, EL(Γ^)=.

Using the results of the previous section, we have

EL(Γ)=EL(Γ0Γ^)EL(Γ0).

We have already seen that EL(Γ0)EL(Γ*). Thus, EL(Γ)EL(Γ*). The reverse inequality holds by symmetry, and conformal invariance is therefore established.

Some applications of extremal length

By the calculation of the extremal distance in an annulus and the conformal invariance it follows that the annulus {z:r<|z|<R} (where 0r<R) is not conformally homeomorphic to the annulus {w:r*<|w|<R*} if RrR*r*.

Extremal length in higher dimensions

The notion of extremal length adapts to the study of various problems in dimensions 3 and higher, especially in relation to quasiconformal mappings.

Template:Expand section

Discrete extremal length

Suppose that G=(V,E) is some graph and Γ is a collection of paths in G. There are two variants of extremal length in this setting. To define the edge extremal length, originally introduced by R. J. Duffin,[2] consider a function ρ:E[0,). The ρ-length of a path is defined as the sum of ρ(e) over all edges in the path, counted with multiplicity. The "area" A(ρ) is defined as eEρ(e)2. The extremal length of Γ is then defined as before. If G is interpreted as a resistor network, where each edge has unit resistance, then the effective resistance between two sets of veritces is precisely the edge extremal length of the collection of paths with one endpoint in one set and the other endpoint in the other set. Thus, discrete extremal length is useful for estimates in discrete potential theory.

Another notion of discrete extremal length that is appropriate in other contexts is vertex extremal length, where ρ:V[0,), the area is A(ρ):=vVρ(v)2, and the length of a path is the sum of ρ(v) over the vertices visited by the path, with multiplicity.

Notes

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

References

  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  1. Ahlfors (1973)
  2. Duffin 1962