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{{Differential equations}} | |||
In mathematics and physics, '''nonlinear partial differential''' equations are (as their name suggests) [[partial differential equations]] with nonlinear terms. They describe many different physical systems, ranging from gravitation to fluid dynamics, and have been used in mathematics to solve problems such as the [[Poincaré conjecture]] and the [[Calabi conjecture]]. They are difficult to study: there are almost no general techniques that work for all such equations, and usually each individual equation has to be studied as a separate problem. | |||
==Methods for studying nonlinear partial differential equations== | |||
===Existence and uniqueness of solutions=== | |||
A fundamental question for any PDE is the existence and uniqueness of a solution for given boundary conditions. For nonlinear equations these questions are in general very hard: for example, the hardest part of Yau's solution of the Calabi conjecture was the proof of existence for a [[Monge–Ampere equation]]. | |||
===Singularities=== | |||
The basic questions about singularities (their formation, propagation, and removal, and regularity of solutions) are the same as for linear PDE, but as usual much harder to study. In the linear case one can just use spaces of distributions, but nonlinear PDEs are not usually defined on arbitrary distributions, so one replaces spaces of distributions by refinements such as [[Sobolev space]]s. | |||
An example of singularity formation is given by the [[Ricci flow]]: [[Richard Hamilton (mathematician)|Hamilton]] showed that while short time solutions exist, singularities will usually form after a finite time. [[Grigori Perelman|Perelman]]'s solution of the [[Poincaré conjecture]] depended on a deep study of these singularities, where he showed how to continue the solution past the singularities. | |||
===Linear approximation=== | |||
The solutions in a neighborhood of a known solution can sometimes be studied by linearizing the PDE around the solution. This corresponds to studying the tangent space of a point of the moduli space of all solutions. | |||
===Moduli space of solutions=== | |||
Ideally one would like to describe the (moduli) space of all solutions explicitly, and | |||
for some very special PDEs this is possible. (In general this is a hopeless problem: it is unlikely that there is any useful description of all solutions of the [[Navier–Stokes equation]] for example, as this would involve describing all possible fluid motions.) If the equation has a very large symmetry group, then one is usually only interested in the moduli space of solutions modulo the symmetry group, and this is sometimes a finite dimensional compact manifold, possibly with singularities; for example, this happens in the case of the [[Seiberg–Witten equations]]. A slightly more complicated case is the self dual Yang–Mills equations, when the moduli space is finite dimensional but not necessarily compact, though it can often be compactified explicitly. Another case when one can sometimes hope to describe all solutions is the case of completely integrable models, when solutions are sometimes a sort of superposition of solitons; for example, this happens for the [[Korteweg–de Vries equation]]. | |||
===Exact solutions=== | |||
It is often possible to write down some special solutions explicitly in terms of elementary functions (though it is rarely possible to describe all solutions like this). One way of finding such explicit solutions is to reduce the equations to equations of lower dimension, preferably ordinary differential equations, which can often be solved exactly. This can sometimes be done using [[separation of variables]], or by looking for highly symmetric solutions. | |||
Some equations have several different exact solutions. | |||
===Numerical solutions=== | |||
{{main|Numerical partial differential equations}} | |||
Numerical solution on a computer is almost the only method that can be used for getting information about arbitrary systems of PDEs. There has been a lot of work done, but a lot of work still remains on solving certain systems numerically, especially for the Navier–Stokes and other equations related to [[weather prediction]]. | |||
===Lax pair=== | |||
If a system of PDEs can be put into [[Lax pair]] form | |||
:<math>\frac{dL}{dt}=LA-AL</math> | |||
then it usually has an infinite number of first integrals, which help to study it. | |||
===Euler–Lagrange equations=== | |||
Systems of PDEs often arise as the [[Euler–Lagrange equation]]s for a variational problem. Systems of this form can sometimes be solved by finding an extremum of the original variational problem. | |||
===Hamilton equations=== | |||
{{see|Hamiltonian mechanics}} | |||
===Integrable systems=== | |||
{{main |integrable systems}} | |||
PDEs that arise from integrable systems are often the easiest to study, and can sometimes be completely solved. A well-known example is the [[Korteweg–de Vries equation]]. | |||
===Symmetry=== | |||
Some systems of PDEs have large symmetry groups. For example, the [[Yang–Mills equation]]s are invariant under an infinite dimensional [[gauge group]], and many systems of equations (such as the [[Einstein field equations]]) are invariant under diffeomorphisms of the underlying manifold. Any such symmetry groups can usually be used to help study the equations; in particular if one solution is known one can trivially generate more by acting with the symmetry group. | |||
Sometimes equations are parabolic or hyperbolic "modulo the action of some group": for example, the [[Ricci flow]] equation is not quite parabolic, but is "parabolic modulo the action of the diffeomorphism group", which implies that it has most of the good properties of parabolic equations. | |||
===Look it up=== | |||
There are several tables of previously studied PDEs such as {{harv|Polyanin|Zaitsev|2004}} and | |||
{{harv|Zwillinger|1998}} and the tables below. | |||
==List of equations== | |||
<!--The table has been split to make editing easier--> | |||
===A–F=== | |||
:{|class="wikitable" style="background: white; color: black; text-align: left" | |||
|-style="background: #eee" | |||
!Name | |||
!Dim | |||
!Equation | |||
!Applications | |||
|- | |||
|[[Benjamin–Bona–Mahony equation|Benjamin–Bona–Mahony]] | |||
|1+1 | |||
|<math>\displaystyle u_t+u_x+uu_x-u_{xxt}=0</math> | |||
|Fluid mechanics | |||
|- | |||
|[[Benjamin–Ono equation|Benjamin-Ono]] | |||
|1+1 | |||
| <math>\displaystyle u_t+Hu_{xx}+uu_x=0</math> | |||
| internal waves in deep water | |||
|- | |||
|[[Boomeron equation|Boomeron]] | |||
|1+1 | |||
|<math>\displaystyle u_t=\mathbf{b}\cdot\mathbf{v}_x</math> | |||
<math>\displaystyle \mathbf{v}_{xt}=u_{xx}\mathbf{b}+\mathbf{a}\times\mathbf{v}_x- | |||
2\mathbf{v}\times(\mathbf{v}\times\mathbf{b})</math> | |||
|[[Soliton]]s | |||
|- | |||
|[[Born-Infeld equation|Born-Infeld]] | |||
|1+1 | |||
|<math>\displaystyle (1-u_t^2)u_{xx} +2u_xu_tu_{xt}-(1+u_x^2)u_{tt}=0</math> | |||
| | |||
|- | |||
|[[Boussinesq equation (water waves)|Boussinesq]] | |||
| 1+1 | |||
| <math>\displaystyle u_{tt} - u_{xx} - u_{xxxx} - 3(u^2)_{xx} = 0</math> | |||
|Fluid mechanics | |||
|- | |||
|[[Buckmaster equation|Buckmaster]] | |||
|1+1 | |||
|<math>\displaystyle u_t=(u^4)_{xx}+(u^3)_x</math> | |||
|Thin viscous fluid sheet flow | |||
|- | |||
|[[Burgers' equation|Burgers]] | |||
|1+1 | |||
| <math>\displaystyle u_t+uu_x=\nu u_{xx}</math> | |||
|Fluid mechanics | |||
|- | |||
|[[Cahn–Hilliard equation]] | |||
|Any | |||
|<math>\displaystyle \frac{\partial c}{\partial t} = D\nabla^2\left(c^3-c-\gamma\nabla^2 c\right)</math> | |||
|Phase separation | |||
|- | |||
|[[Calabi flow]] | |||
|Any | |||
| | |||
|[[Calabi–Yau manifold]]s | |||
|- | |||
| [[Camassa–Holm equation|Camassa–Holm]] | |||
|1+1 | |||
|<math>u_t + 2\kappa u_x - u_{xxt} + 3 u u_x = 2 u_x u_{xx} + u u_{xxx}\,</math> | |||
|[[Peakon]]s | |||
|- | |||
|[[Carleman equation|Carleman]] | |||
|1+1 | |||
|<math>\displaystyle u_t+u_x=v^2-u^2=v_x-v_t</math> | |||
| | |||
|- | |||
||[[Cauchy momentum equation|Cauchy momentum]] | |||
|any | |||
|<math>\displaystyle \rho \left(\frac{\partial \mathbf{v}}{\partial t} + \mathbf{v} \cdot \nabla \mathbf{v}\right) = \nabla \cdot \sigma + \mathbf{f}</math> | |||
|Momentum transport | |||
|- | |||
|[[Sawada–Kotera equation|Caudrey–Dodd–Gibbon–Sawada–Kotera]] | |||
|1+1 | |||
|Same as (rescaled) Sawada–Kotera | |||
| | |||
|- | |||
|[[Chiral field equation|Chiral field]] | |||
|1+1 | |||
| | |||
| | |||
|- | |||
|[[Clairaut equation]] | |||
|any | |||
|<math>x\cdot Du+f(Du)=u</math> | |||
|[[Differential geometry]] | |||
|- | |||
|[[Complex Monge-Ampère equation|Complex Monge–Ampère]] | |||
|Any | |||
|<math>\displaystyle \det(\partial_{i\bar j}\phi) = </math> lower order terms | |||
|[[Calabi conjecture]] | |||
|- | |||
|[[Davey–Stewartson equation|Davey–Stewartson]] | |||
|1+2 | |||
|<math>\displaystyle i u_t + c_0 u_{xx} + u_{yy} = c_1 |u|^2 u + c_2 u \phi_x</math> | |||
<math>\displaystyle \phi_{xx} + c_3 \phi_{yy} = ( |u|^2 )_x</math> | |||
|Finite depth waves | |||
|- | |||
|[[Degasperis–Procesi equation|Degasperis–Procesi]] | |||
|1+1 | |||
|<math>\displaystyle u_t - u_{xxt} + 4u u_x = 3 u_x u_{xx} + u u_{xxx}</math> | |||
|[[Peakon]]s | |||
|- | |||
|[[Dispersive long wave equation|Dispersive long wave]] | |||
|1+1 | |||
|<math>\displaystyle u_t=(u^2-u_x+2w)_x</math>, <math>w_t=(2uw+w_x)_x</math> | |||
| | |||
|- | |||
|[[Drinfeld–Sokolov–Wilson equation|Drinfeld–Sokolov–Wilson]] | |||
|1+1 | |||
|<math>\displaystyle u_t=3ww_x</math> | |||
<math>\displaystyle w_t=2w_{xxx}+2uw_x+u_xw</math> | |||
| | |||
|- | |||
|[[Dym equation]] | |||
|1+1 | |||
|<math>\displaystyle u_t = u^3u_{xxx}.\,</math> | |||
|[[Soliton]]s | |||
|- | |||
|[[Eckhaus equation]] | |||
|1+1 | |||
|<math>iu_t+u_{xx}+2|u|^2_xu+|u|^4u=0</math> | |||
|[[Integrable systems]] | |||
|- | |||
|[[Eikonal equation]] | |||
|any | |||
|<math>\displaystyle |\nabla u(x)|=F(x), \ x\in \Omega</math> | |||
|optics | |||
|- | |||
|[[Einstein field equations]] | |||
| Any | |||
|<math>\displaystyle R_{ab} - {\textstyle 1 \over 2}R\,g_{ab} = \kappa T_{ab} </math> | |||
|[[General relativity]] | |||
|- | |||
|[[Ernst equation]] | |||
|2 | |||
|<math>\displaystyle \Re(u)(u_{rr}+u_r/r+u_{zz}) = (u_r)^2+(u_z)^2</math> | |||
| | |||
|- | |||
|[[Euler equations]] | |||
|1+3 | |||
|<math> | |||
\begin{align} | |||
&\frac{\partial\rho}{\partial t}+\nabla\cdot(\rho\mathbf{u})=0\\ | |||
&\frac{\partial\rho\mathbf{u}}{\partial t}+\nabla\cdot(\mathbf{u}\otimes(\rho \mathbf{u}))+\nabla p=0\\ | |||
&\frac{\partial E}{\partial t}+\nabla\cdot(\mathbf{u}(E+p))=0, | |||
\end{align} | |||
</math> | |||
|non-viscous fluids | |||
|- | |||
|[[Fisher's equation]] | |||
|1+1 | |||
|<math>\displaystyle \frac{\partial u}{\partial t}=u(1-u)+\frac{\partial^2 u}{\partial x^2}.\, </math> | |||
|Gene propagation | |||
|- | |||
|[[FitzHugh–Nagumo model|Fitzhugh-Nagumo]] | |||
|1+1 | |||
|<math>\displaystyle u_t=u_{xx}+u(u-a)(1-u)+w</math> | |||
<math>\displaystyle w_t=\epsilon u</math> | |||
| | |||
|} | |||
===G–K=== | |||
:{|class="wikitable" style="background: white; color: black; text-align: left" | |||
|-style="background: #eee" | |||
!Name | |||
!Dim | |||
!Equation | |||
!Applications | |||
|- | |||
|[[Gardner equation]] | |||
|1+1 | |||
|<math>\displaystyle u_t=6(u+\epsilon^2u^2)u_x+u_{xxx}</math> | |||
| | |||
|- | |||
|[[Garnier equation]] | |||
| | |||
| | |||
| isomonodromic deformations | |||
|- | |||
|[[Gauss–Codazzi equations|Gauss–Codazzi]] | |||
| | |||
| | |||
| surfaces | |||
<!-- | |||
|- | |||
|[[ Generic scalar transport equation|Generic scalar transport ]] | |||
|1+3 | |||
|<math>\displaystyle \frac{\partial \phi}{\partial t } + \nabla \cdot f(t,x,\phi,\nabla\phi) = g(t,x,\phi) </math> | |||
|transport | |||
--> | |||
|- | |||
|[[Ginzburg–Landau equation|Ginzburg–Landau]] | |||
|1+3 | |||
|<math>\displaystyle \alpha \psi + \beta |\psi|^2 \psi + \frac{1}{2m} \left(-i\hbar\nabla - 2e\mathbf{A} \right)^2 \psi = 0 </math> | |||
|Superconductivity | |||
|- | |||
|[[Gross–Neveu model|Gross–Neveu]] | |||
|1+1 | |||
| | |||
| | |||
|- | |||
|[[Gross–Pitaevskii equation|Gross–Pitaevskii]] | |||
|1+''n'' | |||
|<math>\displaystyle i\partial_t\psi = (-\tfrac12\Delta^2 + V(x) + g|\psi|^2) \psi </math> | |||
| [[Bose–Einstein condensate]] | |||
|- | |||
|[[Hartree equation]] | |||
|Any | |||
|<math>\displaystyle i\partial_tu + \Delta u= V(u)u</math> | |||
where | |||
<math>\displaystyle V(u)= \pm |x|^{-n} * |u|^2</math>. | |||
| | |||
|- | |||
|[[Hasegawa–Mima equation|Hasegawa–Mima]] | |||
|1+3 | |||
|<math>\displaystyle | |||
0=\frac{\partial}{\partial t}\left(\nabla^2\phi-\phi\right)</math> | |||
<math>\displaystyle -\left[\left(\nabla\phi\times \mathbf{\hat z}\right)\cdot\nabla\right]\left[\nabla^2\phi-\ln\left(\frac{n_0}{\omega_{ci}}\right)\right] | |||
</math> | |||
|Turbulence in plasma | |||
|- | |||
|[[Heisenberg ferromagnet]] | |||
|1+1 | |||
|<math>\displaystyle \mathbf{S}_t=\mathbf{S}\wedge \mathbf{S}_{xx}. </math> | |||
|Magnetism | |||
|- | |||
|[[Hirota equation]] | |||
|1+1 | |||
| | |||
| | |||
|- | |||
|[[Hirota–Satsuma equation|Hirota–Satsuma]] | |||
|1+1 | |||
|<math>\displaystyle u_t=u_{xxx}/2 +3uu_x-6ww_x</math>, | |||
<math>\displaystyle w_t+w_{xxx}+3uw_x=0</math> | |||
| | |||
|- | |||
|[[Hunter–Saxton equation|Hunter–Saxton]] | |||
|1+1 | |||
|<math>\displaystyle | |||
(u_t + u u_x)_x = \frac{1}{2} \, u_x^2 | |||
</math> | |||
|[[Liquid crystal]]s | |||
|- | |||
|[[Ishimori equation]] | |||
|1+2 | |||
|<math>\displaystyle \frac{\partial \mathbf{S}}{\partial t} = \mathbf{S}\wedge \left(\frac{\partial^2 \mathbf{S}}{\partial x^{2}} + \frac{\partial^2 \mathbf{S}}{\partial y^{2}}\right)+ \frac{\partial u}{\partial x}\frac{\partial \mathbf{S}}{\partial y} + \frac{\partial u}{\partial y}\frac{\partial \mathbf{S}}{\partial x}</math> | |||
<math>\displaystyle \frac{\partial^2 u}{\partial x^2}-\alpha^2 \frac{\partial^2 u}{\partial y^2}=-2\alpha^2 \mathbf{S}\cdot\left(\frac{\partial \mathbf{S}}{\partial x}\wedge \frac{\partial \mathbf{S}}{\partial y}\right)</math> | |||
|[[Integrable systems]] | |||
|- | |||
|[[Kadomtsev–Petviashvili equation|Kadomtsev –Petviashvili]] | |||
|1+2 | |||
|<math>\displaystyle \partial_x(\partial_t u+u \partial_x u+\epsilon^2\partial_{xxx}u)+\lambda\partial_{yy}u=0</math> | |||
|Shallow water waves | |||
|- | |||
|[[von Karman equation|von Karman]] | |||
|2 | |||
|<math>\displaystyle \nabla^4 u = E(w_{xy}^2-w_{xx}w_{yy})</math>, <math>\displaystyle \nabla^4w = a+b(u_{yy}w_{xx}+u_{xx}w_{yy}-2u_{xy}w_{xy}</math> | |||
| | |||
|- | |||
|[[Kaup equation|Kaup]] | |||
|1+1 | |||
|<math>\displaystyle f_x=2fgc(x-t)=g_t</math> | |||
| | |||
|- | |||
|[[Kaup–Kupershmidt equation|Kaup–Kupershmidt]] | |||
|1+1 | |||
|<math>\displaystyle u_t = u_{xxxxx}+10u_{xxx}u+25u_{xx}u_x+20u^2u_x </math> | |||
|[[Integrable systems]] | |||
|- | |||
|[[Klein–Gordon–Maxwell equation|Klein–Gordon–Maxwell]] | |||
|any | |||
|<math>\displaystyle \nabla^2s=(|\mathbf a|^2+1)s</math>, <math>\displaystyle \nabla^2\mathbf a =\nabla(\nabla\cdot\mathbf a)+s^2\mathbf a</math> | |||
| | |||
|- | |||
|[[Non-linear Klein–Gordon equation|Klein–Gordon (nonlinear)]] | |||
|any | |||
|<math>\nabla^2u+\lambda u^p=0</math> | |||
| | |||
|- | |||
|[[Klein–Gordon–Zakharov system|Klein–Gordon–Zakharov]] | |||
| | |||
| | |||
| | |||
|- | |||
|[[Khokhlov–Zabolotskaya equation|Khokhlov–Zabolotskaya]] | |||
|1+2 | |||
|<math>\displaystyle u_{xt} -(uu_x)_x =u_{yy}</math> | |||
| | |||
|- | |||
|[[Korteweg–de Vries equation|Korteweg–de Vries]] (KdV) | |||
|1+1 | |||
|<math>\displaystyle \partial_tu+\partial^3_x u+6u\partial_x u=0</math> | |||
|Shallow waves, [[Integrable systems]] | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries equation|KdV (cylinderical)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \partial_x^3 u - 6u\partial_x u + u/2t = 0</math> | |||
| | |||
--> | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries equation|KdV (deformed)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + (u_{xx}-2\eta u^3-3uu_x^2/2(\eta+u^2))_x = 0</math> | |||
| | |||
--> | |||
<!-- | |||
|- | |||
|[[ Generalized Korteweg–de Vries equation|KdV (generalized)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \partial_x^3 u = \partial_x^5 u </math> | |||
| | |||
--> | |||
|- | |||
|[[Generalized Korteweg–de Vries equation|KdV (generalized)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \partial_x^3 u + \partial_x f(u) = 0</math> | |||
| | |||
|- | |||
|[[Korteweg–de Vries equation|KdV (modified)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \partial_x^3 u \pm 6u^2\partial_x u = 0</math> | |||
| | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries equation|KdV (modified modified)]] | |||
|1+1 | |||
|<math>\displaystyle u_t + u_{xxx} -u_x^3/8+u_x(Ae^{au}+B+Ce^{-au}) = 0</math> | |||
| | |||
--> | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries equation|KdV (spherical)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \partial_x^3 u - 6\partial_x u + u/t = 0</math> | |||
| | |||
--> | |||
|- | |||
|[[Super Korteweg–de Vries equation|KdV (super)]] | |||
|1+1 | |||
|<math>\displaystyle u_t=6uu_x-u_{xxx}+3ww_{xx}</math>, <math>\displaystyle w_t=3u_xw+6uw_x-4w_{xxx}</math> | |||
| | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries equation|KdV (transitional)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \partial_x^3 u - 6f(t)u\partial_x u = 0</math> | |||
| | |||
--> | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries equation|KdV (variable coefficients)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \beta t^n\partial_x^3 u +\alpha t^nu\partial_x u= 0</math> | |||
| | |||
--> | |||
<!-- | |||
|- | |||
|[[ Korteweg–de Vries–Burgers equation|KdV (Burgers)]] | |||
|1+1 | |||
|<math>\displaystyle \partial_t u + \mu\partial_x^3 u +2u\partial_x u -\nu u_{xx} = 0</math> | |||
| | |||
--> | |||
|- | |||
|colspan="4" |There are more minor variations listed in the article on [[KdV equation]]s. | |||
|- | |||
|[[Kuramoto–Sivashinsky equation|Kuramoto–Sivashinsky]] | |||
|1+''n'' | |||
|<math>\displaystyle u_t+\nabla^4u+\nabla^2u+|\nabla u|^2/2=0</math> | |||
| | |||
|} | |||
===L–Q=== | |||
:{|class="wikitable" style="background: white; color: black; text-align: left" | |||
|-style="background: #eee" | |||
!Name | |||
!Dim | |||
!Equation | |||
!Applications | |||
|- | |||
|[[Landau–Lifshitz model]] | |||
|1+''n'' | |||
|<math>\displaystyle \frac{\partial \mathbf{S}}{\partial t} = \mathbf{S}\wedge \sum_i\frac{\partial^2 \mathbf{S}}{\partial x_i^{2}} + \mathbf{S}\wedge J\mathbf{S}</math> | |||
|Magnetic field in solids | |||
|- | |||
|[[Lin-Tsien equation]] | |||
|1+2 | |||
| <math>\displaystyle 2u_{tx}+u_xu_{xx}-u_{yy}</math> | |||
| | |||
|- | |||
|[[Liouville equation|Liouville]] | |||
|any | |||
|<math>\displaystyle \nabla^2u+e^{\lambda u}=0</math> | |||
| | |||
|- | |||
|[[Minimal surface equation|Minimal surface]] | |||
|3 | |||
|<math>\displaystyle \operatorname{div}(Du/\sqrt{1+|Du|^2})=0</math> | |||
|[[minimal surface]]s | |||
|- | |||
|[[Molenbroeck equation|Molenbroeck]] | |||
|2 | |||
| | |||
| | |||
|- | |||
|[[Monge–Ampère equation|Monge–Ampère]] | |||
|any | |||
|<math>\displaystyle \det(\partial_{ij}\phi) = </math> lower order terms | |||
| | |||
|- | |||
|[[Navier–Stokes equations|Navier–Stokes]]<br>[[Derivation of the Navier–Stokes equations|(and its derivation)]] | |||
|1+3 | |||
|<math> \displaystyle | |||
\rho \left( \frac{\partial v_i}{\partial t} | |||
+ v_j \frac{\partial v_i}{\partial x_j} \right) = | |||
- \frac{\partial p}{\partial x_i} | |||
+ \frac{\partial}{\partial x_j} \left[ | |||
\mu \left( \frac{\partial v_i}{\partial x_j} + \frac{\partial v_j}{\partial x_i} \right) | |||
+ \lambda \frac{\partial v_k}{\partial x_k} | |||
\right] | |||
+ f_i | |||
</math><br> | |||
+ mass conservation: <math>\frac{\partial \rho}{\partial t} + \frac{\partial \left( \rho\, v_i \right)}{\partial x_i} = 0</math><br> | |||
+ an [[equation of state]] to relate ''p'' and ''ρ'', ''e.g.'' for an [[incompressible flow]]: <math>\frac{\partial v_i}{\partial x_i} = 0 </math> | |||
|Fluid flow | |||
|- | |||
|[[Nonlinear Schrödinger equation|Nonlinear Schrödinger (cubic)]] | |||
|1+1 | |||
|<math>\displaystyle i\partial_t\psi=-{1\over 2}\partial^2_x\psi+\kappa|\psi|^2 \psi</math> | |||
|optics, water waves | |||
|- | |||
|[[Nonlinear Schrödinger equation|Nonlinear Schrödinger (derivative)]] | |||
|1+1 | |||
|<math>\displaystyle i\partial_t\psi=-{1\over 2}\partial^2_x\psi+\partial_x(i\kappa|\psi|^2 \psi)</math> | |||
|optics, water waves | |||
|- | |||
|[[Novikov–Veselov equation]] | |||
|1+2 | |||
| see Veselov–Novikov equation below | |||
| | |||
|- | |||
|[[Omega equation]] | |||
|1+3 | |||
|<math>\displaystyle \nabla^2\omega + \frac{f^2}{\sigma}\frac{\partial^2\omega}{\partial p^2} </math> <math>\displaystyle = \frac{f}{\sigma}\frac{\partial}{\partial p}\mathbf{V}_g\cdot\nabla_p (\zeta_g + f) + \frac{R}{\sigma p}\nabla^2_p(\mathbf{V}_g\cdot\nabla_p T)</math> | |||
|atmospheric physics | |||
|- | |||
|[[Plateau equation|Plateau]] | |||
|2 | |||
|<math>\displaystyle (1+u_y^2)u_{xx} -2u_xu_yu_{xy} +(1+u_x^2)u_{yy}=0</math> | |||
| | |||
|- | |||
|[[Pohlmeyer–Lund–Regge equation|Pohlmeyer–Lund–Regge]] | |||
|2 | |||
|<math>\displaystyle u_{xx}-u_{yy}\pm \sin u \cos u +\frac{\cos u}{\sin^3 u}(v_x^2-v_y^2)=0</math> | |||
<math>\displaystyle (v_x\cot^2u)_x = (v_y\cot^2 u)_y</math> | |||
| | |||
|- | |||
|[[Porous medium equation|Porous medium]] | |||
|1+''n'' | |||
|<math>\displaystyle u_t=\Delta(u^\gamma)</math> | |||
|diffusion | |||
|- | |||
|[[Prandtl equation|Prandtl]] | |||
|1+2 | |||
|<math>\displaystyle u_t+uu_x+vu_y=U_t+UU_x+\frac{\mu}{\rho}u_{yy}</math>, <math>\displaystyle u_x+v_y=0</math> | |||
|boundary layer | |||
|- | |||
|[[Primitive equations]] | |||
|1+3 | |||
| | |||
|Atmospheric models | |||
|} | |||
===R–Z, α–ω=== | |||
:{|class="wikitable" style="background: white; color: black; text-align: left" | |||
|-style="background: #eee" | |||
!Name | |||
!Dim | |||
!Equation | |||
!Applications | |||
|- | |||
|[[Rayleigh equation|Rayleigh]] | |||
|2 | |||
|<math>\displaystyle u_{tt}-u_{xx} = \epsilon(u_t-u_t^3)</math> | |||
| | |||
|- | |||
|[[Ricci flow]] | |||
|Any | |||
|<math>\displaystyle \partial_t g_{ij}=-2 R_{ij}</math> | |||
|[[Poincaré conjecture]] | |||
|- | |||
|[[Richards equation]] | |||
|1+3 | |||
|<math>\displaystyle \frac{\partial \theta}{\partial t}= \frac{\partial}{\partial z} | |||
\left[ K(\psi) \left (\frac{\partial \psi}{\partial z} + 1 \right) \right]\ | |||
</math> | |||
|Variably saturated flow in porous media | |||
|- | |||
|[[Sawada–Kotera equation|Sawada–Kotera]] | |||
|1+1 | |||
|<math>\displaystyle u_t+45u^2u_x+15u_xu_{xx}+15uu_{xxx}+u_{xxxxx}=0</math> | |||
| | |||
|- | |||
|[[Schlesinger equations|Schlesinger]] | |||
| Any | |||
|<math>\displaystyle | |||
\begin{align} | |||
{\partial A_i \over \partial t_j} &= {\left[ A_i, \ A_j \right] \over t_i - t_j}, \quad i\neq j \\ | |||
{\partial A_i \over \partial t_i} &=- \sum_{j=1 \atop j\neq i}^n {\left[ A_i, \ A_j \right] \over t_i - t_j}, \quad 1\leq i, j \leq n | |||
\end{align} | |||
</math> | |||
|[[isomonodromic deformations]] | |||
|- | |||
|[[Seiberg–Witten equations|Seiberg–Witten]] | |||
|1+3 | |||
|<math>\displaystyle D^A\phi=0, \qquad F^+_A=\sigma(\phi)</math> | |||
|[[Seiberg–Witten invariant]]s, [[Quantum field theory|QFT]] | |||
|- | |||
|[[Shallow water equations|Shallow water]] | |||
|1+2 | |||
|<math>\displaystyle | |||
\begin{align} | |||
\frac{\partial \eta }{\partial t} + \frac{\partial (\eta u)}{\partial x} + \frac{\partial (\eta v)}{\partial y} = 0\\[3pt] | |||
\frac{\partial (\eta u)}{\partial t}+ \frac{\partial}{\partial x}\left( \eta u^2 + \frac{1}{2}g \eta^2 \right) + \frac{\partial (\eta u v)}{\partial y} = 0\\[3pt] | |||
\frac{\partial (\eta v)}{\partial t} + \frac{\partial (\eta uv)}{\partial x} + \frac{\partial}{\partial y}\left(\eta v^2 + \frac{1}{2}g \eta ^2\right) = 0 | |||
\end{align} | |||
</math> | |||
|shallow water waves | |||
|- | |||
|[[Sine–Gordon equation|Sine–Gordon]] | |||
|1+1 | |||
|<math>\displaystyle \, \phi_{tt}- \phi_{xx} + \sin\phi = 0</math> | |||
|[[Soliton]]s, [[Quantum field theory|QFT]] | |||
|- | |||
|[[Sinh–Gordon equation|Sinh–Gordon]] | |||
|1+1 | |||
|<math>\displaystyle u_{xt}= \sinh u </math> | |||
|[[Soliton]]s, [[Quantum field theory|QFT]] | |||
|- | |||
|[[Sinh–Poisson equation|Sinh–Poisson]] | |||
|1+''n'' | |||
|<math>\displaystyle \nabla^2u+\sinh u=0</math> | |||
| | |||
|- | |||
|[[Swift–Hohenberg equation|Swift–Hohenberg]] | |||
|any | |||
|<math>\displaystyle | |||
\frac{\partial u}{\partial t} = r u - (1+\nabla^2)^2u + N(u) | |||
</math> | |||
|pattern forming | |||
|- | |||
|[[Three-wave equation]] | |||
|1+''n'' | |||
| | |||
|[[Integrable systems]] | |||
|- | |||
|[[Thomas equation]] | |||
|2 | |||
|<math>\displaystyle u_{xy}+\alpha u_x+\beta u_y+\gamma u_xu_y=0</math> | |||
| | |||
|- | |||
|[[Thirring model]] | |||
|1+1 | |||
|<math>\displaystyle iu_x+v+u|v|^2=0</math>, <math>\displaystyle iv_t+u+v|u|^2=0</math> | |||
|Dirac field, [[Quantum field theory|QFT]] | |||
|- | |||
|[[Toda lattice]] | |||
|any | |||
|<math>\displaystyle \nabla^2\log u_n = u_{n+1}-2u_n+u_{n-1}</math> | |||
| | |||
|- | |||
|[[Novikov–Veselov equation|Veselov–Novikov equation]] | |||
|1+2 | |||
|<math>\displaystyle (\partial_t+\partial_z^3+\partial_{\bar z}^3)v+\partial_z(uv)+\partial_{\bar z}(uw) =0</math>, <math>\displaystyle \partial_{\bar z}u=3\partial_zv</math>, <math>\displaystyle \partial_zw=3\partial_{\bar z} v</math> | |||
| shallow water waves | |||
|- | |||
|[[Wadati–Konno–Ichikawa–Schimizu equation|Wadati–Konno–Ichikawa–Schimizu]] | |||
|1+1 | |||
|<math>\displaystyle iu_t+((1+|u|^2)^{-1/2}u)_{xx}=0</math> | |||
| | |||
|- | |||
|[[WDVV equations]] | |||
|Any | |||
|<math>\displaystyle | |||
\sum_{\sigma, \tau = 1}^n\left({\partial^3 F \over \partial t^\alpha t^\beta t^\sigma} \eta^{\sigma \tau} {\partial^3 F \over \partial t^\mu t^\nu t^\tau} \right) </math> <math>\displaystyle | |||
= \sum_{\sigma, \tau = 1}^n\left({\partial^3 F \over \partial t^\alpha t^\nu t^\sigma} \eta^{\sigma \tau} {\partial^3 F \over \partial t^\mu t^\beta t^\tau} \right) | |||
</math> | |||
|[[Topological field theory]], [[Quantum field theory|QFT]] | |||
|- | |||
|[[WZW model]] | |||
|1+1 | |||
| | |||
|[[Quantum field theory|QFT]] | |||
|- | |||
|[[Whitham equation]] | |||
|1+1 | |||
|<math>\displaystyle \eta_t + \alpha \eta \eta_x + \int_{-\infty}^{+\infty} K(x-\xi)\, \eta_\xi(\xi,t)\, \text{d}\xi = 0</math> | |||
|[[water wave]]s | |||
|- | |||
|[[Yamabe problem|Yamabe]] | |||
|''n'' | |||
|<math>\displaystyle\Delta \phi+h(x)\phi = \lambda f(x)\phi^{(n+2)/(n-2)}</math> | |||
|[[Differential geometry]] | |||
|- | |||
|[[Yang–Mills equations|Yang–Mills equation (source-free)]] | |||
|Any | |||
|<math>\displaystyle D_\mu F^{\mu\nu}=0, \quad F_{\mu \nu} = A_{\mu, \nu} - A_{\nu, \mu }+ [A_\mu, \, A_\nu] | |||
</math> | |||
|[[Gauge theory]], [[Quantum field theory|QFT]] | |||
|- | |||
|[[Instanton|Yang–Mills (self-dual/anti-self-dual)]] | |||
| 4 | |||
| <math> F_{\alpha \beta} = \pm \epsilon_{\alpha \beta \mu \nu} F^{\mu \nu}, | |||
\quad F_{\mu \nu} = A_{\mu, \nu} - A_{\nu, \mu }+ [A_\mu, \, A_\nu] | |||
</math> | |||
| [[Instantons]], [[Donaldson theory]], [[Quantum field theory|QFT]] | |||
|- | |||
|[[Yukawa equation]] | |||
|1+''n'' | |||
|<math>\displaystyle i \partial_t^{}u + \Delta u = -A u</math> | |||
<math>\displaystyle\Box A = m^2_{} A + |u|^2 </math> | |||
|[[Meson]]-[[nucleon]] interactions, [[Quantum field theory|QFT]] | |||
|- | |||
|[[Zakharov system]] | |||
|1+3 | |||
|<math>\displaystyle i \partial_t^{} u + \Delta u = un</math> | |||
<math>\displaystyle \Box n = -\Delta (|u|^2_{})</math> | |||
|[[Langmuir wave]]s | |||
|- | |||
|[[Zakharov–Schulman system|Zakharov–Schulman]] | |||
|1+3 | |||
|<math>\displaystyle iu_t + L_1u = \phi u</math> | |||
<math>\displaystyle L_2 \phi = L_3( | u |^2)</math> | |||
|Acoustic waves | |||
|- | |||
|[[Zoomeron equation|Zoomeron]] | |||
|1+1 | |||
|<math>\displaystyle (u_{xt}/u)_{tt}-(u_{xt}/u)_{xx} +2(u^2)_{xt}=0</math> | |||
|[[Soliton]]s | |||
|- | |||
|[[Quartic interaction|φ<sup>4</sup> equation]] | |||
|1+1 | |||
|<math>\displaystyle \phi_{tt}-\phi_{xx}-\phi+\phi^3=0</math> | |||
| [[quantum field theory|QFT]] | |||
|- | |||
|[[Non-linear sigma model|σ-model]] | |||
|1+1 | |||
|<math>\displaystyle {\mathbf v}_{xt}+({\mathbf v}_x{\mathbf v}_t){\mathbf v}=0</math> | |||
|[[Harmonic map]]s, [[integrable systems]], [[Quantum field theory|QFT]] | |||
|} | |||
==See also== | |||
*[[Euler–Lagrange equation]] | |||
*[[Nonlinear system]] | |||
*[[Integrable system]] | |||
*[[Inverse scattering transform]] | |||
*[[Dispersive partial differential equation]] | |||
==References== | |||
*{{citation|mr=0680040|author1-link=Francesco Calogero|author2-link=Antonio Degasperis | |||
|last=Calogero|first= Francesco|last2= Degasperis|first2= Antonio | |||
|title=Spectral transform and solitons. Vol. I. Tools to solve and investigate nonlinear evolution equations|series= Studies in Mathematics and its Applications|volume= 13|publisher= North-Holland Publishing Co.|place= Amsterdam-New York|year= 1982| ISBN=0-444-86368-0 }} | |||
*{{springer|id=N/n067170|first=S.I.|last= Pokhozhaev|title=Non-linear partial differential equation}} | |||
*{{citation|mr=2042347 | |||
|last=Polyanin|first= Andrei D.|last2= Zaitsev|first2= Valentin F. | |||
|title=Handbook of nonlinear partial differential equations|publisher= Chapman & Hall/CRC|place= Boca Raton, FL|year= 2004|pages= xx+814 | ISBN= 1-58488-355-3}} | |||
*{{citation|editor-last=Scott|editor-first=Alwyn |title=Encyclopedia of Nonlinear Science|year=2004|publisher=Routledge|isbn=978-1-57958-385-9}}. For errata, see [http://personal.riverusers.com/~rover/typosens.html this] | |||
*{{citation|mr=0977062 | |||
|last=Zwillinger|first= Daniel | |||
|title=Handbook of differential equations|publisher= Academic Press, Inc.|place= Boston, MA|edition=3rd|year= 1998|ISBN= 978-0-12-784396-4}} | |||
==External links== | |||
*[http://eqworld.ipmnet.ru/ EqWorld, The World of Mathematical Equations] | |||
*[http://tosio.math.toronto.edu/wiki/index.php/Main_Page dispersive PDE wiki] | |||
*[http://www.primat.mephi.ru/wiki/ NEQwiki, the nonlinear equations encyclopedia] | |||
[[Category:Partial differential equations|nonlinear]] | |||
[[Category:Solitons]] | |||
[[Category:Differential geometry]] | |||
[[Category:Exactly solvable models]] |
Revision as of 11:40, 6 May 2013
Template:Differential equations
In mathematics and physics, nonlinear partial differential equations are (as their name suggests) partial differential equations with nonlinear terms. They describe many different physical systems, ranging from gravitation to fluid dynamics, and have been used in mathematics to solve problems such as the Poincaré conjecture and the Calabi conjecture. They are difficult to study: there are almost no general techniques that work for all such equations, and usually each individual equation has to be studied as a separate problem.
Methods for studying nonlinear partial differential equations
Existence and uniqueness of solutions
A fundamental question for any PDE is the existence and uniqueness of a solution for given boundary conditions. For nonlinear equations these questions are in general very hard: for example, the hardest part of Yau's solution of the Calabi conjecture was the proof of existence for a Monge–Ampere equation.
Singularities
The basic questions about singularities (their formation, propagation, and removal, and regularity of solutions) are the same as for linear PDE, but as usual much harder to study. In the linear case one can just use spaces of distributions, but nonlinear PDEs are not usually defined on arbitrary distributions, so one replaces spaces of distributions by refinements such as Sobolev spaces.
An example of singularity formation is given by the Ricci flow: Hamilton showed that while short time solutions exist, singularities will usually form after a finite time. Perelman's solution of the Poincaré conjecture depended on a deep study of these singularities, where he showed how to continue the solution past the singularities.
Linear approximation
The solutions in a neighborhood of a known solution can sometimes be studied by linearizing the PDE around the solution. This corresponds to studying the tangent space of a point of the moduli space of all solutions.
Moduli space of solutions
Ideally one would like to describe the (moduli) space of all solutions explicitly, and for some very special PDEs this is possible. (In general this is a hopeless problem: it is unlikely that there is any useful description of all solutions of the Navier–Stokes equation for example, as this would involve describing all possible fluid motions.) If the equation has a very large symmetry group, then one is usually only interested in the moduli space of solutions modulo the symmetry group, and this is sometimes a finite dimensional compact manifold, possibly with singularities; for example, this happens in the case of the Seiberg–Witten equations. A slightly more complicated case is the self dual Yang–Mills equations, when the moduli space is finite dimensional but not necessarily compact, though it can often be compactified explicitly. Another case when one can sometimes hope to describe all solutions is the case of completely integrable models, when solutions are sometimes a sort of superposition of solitons; for example, this happens for the Korteweg–de Vries equation.
Exact solutions
It is often possible to write down some special solutions explicitly in terms of elementary functions (though it is rarely possible to describe all solutions like this). One way of finding such explicit solutions is to reduce the equations to equations of lower dimension, preferably ordinary differential equations, which can often be solved exactly. This can sometimes be done using separation of variables, or by looking for highly symmetric solutions.
Some equations have several different exact solutions.
Numerical solutions
Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. Numerical solution on a computer is almost the only method that can be used for getting information about arbitrary systems of PDEs. There has been a lot of work done, but a lot of work still remains on solving certain systems numerically, especially for the Navier–Stokes and other equations related to weather prediction.
Lax pair
If a system of PDEs can be put into Lax pair form
then it usually has an infinite number of first integrals, which help to study it.
Euler–Lagrange equations
Systems of PDEs often arise as the Euler–Lagrange equations for a variational problem. Systems of this form can sometimes be solved by finding an extremum of the original variational problem.
Hamilton equations
Integrable systems
Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. PDEs that arise from integrable systems are often the easiest to study, and can sometimes be completely solved. A well-known example is the Korteweg–de Vries equation.
Symmetry
Some systems of PDEs have large symmetry groups. For example, the Yang–Mills equations are invariant under an infinite dimensional gauge group, and many systems of equations (such as the Einstein field equations) are invariant under diffeomorphisms of the underlying manifold. Any such symmetry groups can usually be used to help study the equations; in particular if one solution is known one can trivially generate more by acting with the symmetry group.
Sometimes equations are parabolic or hyperbolic "modulo the action of some group": for example, the Ricci flow equation is not quite parabolic, but is "parabolic modulo the action of the diffeomorphism group", which implies that it has most of the good properties of parabolic equations.
Look it up
There are several tables of previously studied PDEs such as Template:Harv and Template:Harv and the tables below.
List of equations
A–F
Name Dim Equation Applications Benjamin–Bona–Mahony 1+1 Fluid mechanics Benjamin-Ono 1+1 internal waves in deep water Boomeron 1+1 Solitons Born-Infeld 1+1 Boussinesq 1+1 Fluid mechanics Buckmaster 1+1 Thin viscous fluid sheet flow Burgers 1+1 Fluid mechanics Cahn–Hilliard equation Any Phase separation Calabi flow Any Calabi–Yau manifolds Camassa–Holm 1+1 Peakons Carleman 1+1 Cauchy momentum any Momentum transport Caudrey–Dodd–Gibbon–Sawada–Kotera 1+1 Same as (rescaled) Sawada–Kotera Chiral field 1+1 Clairaut equation any Differential geometry Complex Monge–Ampère Any lower order terms Calabi conjecture Davey–Stewartson 1+2 Finite depth waves Degasperis–Procesi 1+1 Peakons Dispersive long wave 1+1 , Drinfeld–Sokolov–Wilson 1+1 Dym equation 1+1 Solitons Eckhaus equation 1+1 Integrable systems Eikonal equation any optics Einstein field equations Any General relativity Ernst equation 2 Euler equations 1+3 non-viscous fluids Fisher's equation 1+1 Gene propagation Fitzhugh-Nagumo 1+1
G–K
Name Dim Equation Applications Gardner equation 1+1 Garnier equation isomonodromic deformations Gauss–Codazzi surfaces Ginzburg–Landau 1+3 Superconductivity Gross–Neveu 1+1 Gross–Pitaevskii 1+n Bose–Einstein condensate Hartree equation Any Hasegawa–Mima 1+3 Turbulence in plasma Heisenberg ferromagnet 1+1 Magnetism Hirota equation 1+1 Hirota–Satsuma 1+1 , Hunter–Saxton 1+1 Liquid crystals Ishimori equation 1+2 Integrable systems Kadomtsev –Petviashvili 1+2 Shallow water waves von Karman 2 , Kaup 1+1 Kaup–Kupershmidt 1+1 Integrable systems Klein–Gordon–Maxwell any , Klein–Gordon (nonlinear) any Klein–Gordon–Zakharov Khokhlov–Zabolotskaya 1+2 Korteweg–de Vries (KdV) 1+1 Shallow waves, Integrable systems KdV (generalized) 1+1 KdV (modified) 1+1 KdV (super) 1+1 , There are more minor variations listed in the article on KdV equations. Kuramoto–Sivashinsky 1+n
L–Q
Name Dim Equation Applications Landau–Lifshitz model 1+n Magnetic field in solids Lin-Tsien equation 1+2 Liouville any Minimal surface 3 minimal surfaces Molenbroeck 2 Monge–Ampère any lower order terms Navier–Stokes
(and its derivation)1+3
+ mass conservation:
+ an equation of state to relate p and ρ, e.g. for an incompressible flow:Fluid flow Nonlinear Schrödinger (cubic) 1+1 optics, water waves Nonlinear Schrödinger (derivative) 1+1 optics, water waves Novikov–Veselov equation 1+2 see Veselov–Novikov equation below Omega equation 1+3 atmospheric physics Plateau 2 Pohlmeyer–Lund–Regge 2 Porous medium 1+n diffusion Prandtl 1+2 , boundary layer Primitive equations 1+3 Atmospheric models
R–Z, α–ω
See also
- Euler–Lagrange equation
- Nonlinear system
- Integrable system
- Inverse scattering transform
- Dispersive partial differential equation
References
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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. For errata, see this - 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