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In [[representation theory]], a branch of mathematics, the '''Whittaker model''' is a realization of a [[Group representation|representation]] of a [[reductive algebraic group]] such as ''GL''<sub>2</sub> over a [[finite field|finite]] or [[local field|local]] or [[global field]] on a space of functions on the group. It is named after [[E. T. Whittaker]] even though he never worked in this area, because {{harvs|last=Jacquet|year1=1966|year2=1967}} pointed out that for the group SL<sub>2</sub>('''R''') some of the functions involved in the representation are [[Whittaker function]]s. | |||
[[Irreducible representation]]s without a Whittaker model are sometimes called "degenerate", and those with a Whittaker model are sometimes called "generic". The representation [[θ10|θ<sub>10</sub>]] of the [[symplectic group]] Sp<sub>4</sub> is the simplest example of a degenerate representation. | |||
==Whittaker models for GL<sub>2</sub>== | |||
If ''G'' is the [[algebraic group]] ''GL''<sub>2</sub> and '''F''' is a local field, | |||
and τ is a fixed non-trivial character of the additive group of '''F''' and π is an irreducible representation of ''G''('''F'''), then the Whittaker model for π is a representation π on a space of functions ''f'' on ''G''('''F''') satisfying | |||
:<math>f\left(\begin{pmatrix}1 & b \\ 0 & 1\end{pmatrix}g\right) = \tau(b)f(g). </math> | |||
{{harvtxt|Jacquet|Langlands|1970}} used Whittaker models to assign L-functions to [[admissible representation]]s of ''GL''<sub>2</sub>. | |||
==Whittaker models for GL<sub>''n''</sub>== | |||
Let <math>G</math> be the [[general linear group]] <math>{\rm GL}_n</math>, <math>\psi</math> a smooth complex valued non-trivial additive character of <math>F</math> and <math>U</math> the subgroup of <math>{\rm GL}_n</math> consisting of unipotent upper triangular matrices. A non-degenerate character on <math>U</math> is of the form | |||
:<math>\chi(u)=\psi(\alpha_1x_{12}+\alpha_2x_{23}+\cdots+\alpha_{n-1}x_{n-1n}),</math> | |||
for <math>u=(x_{ij})</math> ∈ <math>U</math> and non-zero <math>\alpha_1</math>, ..., <math>\alpha_{n-1}</math> ∈ <math>F</math>. If <math>(\pi,V)</math> is a smooth representation of <math>G(F)</math>, a '''Whittaker functional''' <math>\lambda</math> is a continuous linear functional on <math>V</math> such that <math>\lambda(\pi(u)v)=\chi(u)\lambda(v)</math> for all <math>u</math> ∈ <math>U</math>, <math>v</math> ∈ <math>V</math>. '''Multiplicity one''' states that, for <math>\pi</math> unitary irreducible, the space of Whittaker functionals has dimension at most equal to one. | |||
==Whittaker models for reductive groups== | |||
If ''G'' is a split reductive group and ''U'' is the unipotent radical of a Borel subgroup ''B'', then a Whittaker model for a representation is an embedding of it into the induced ([[Gelfand–Graev representation|Gelfand–Graev]]) representation Ind{{su|b=''U''|p=''G''}}(χ), where χ is a non-degenerate character of ''U''. | |||
==See also== | |||
*[[Gelfand–Graev representation]], roughly the sum of Whittaker models over a finite field. | |||
*[[Kirillov model]] | |||
==References== | |||
*{{Citation | last1=Jacquet | first1=Hervé | title=Une interprétation géométrique et une généralisation P-adique des fonctions de Whittaker en théorie des groupes semi-simples | mr=0200390 | year=1966 | journal=Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Séries a et B | issn=0151-0509 | volume=262 | pages=A943––A945}} | |||
*{{Citation | last1=Jacquet | first1=Hervé | title=Fonctions de Whittaker associées aux groupes de Chevalley | url=http://www.numdam.org/item?id=BSMF_1967__95__243_0 | mr=0271275 | year=1967 | journal=Bulletin de la Société Mathématique de France | issn=0037-9484 | volume=95 | pages=243–309}} | |||
*{{Citation | author2-link=Robert Langlands | last1=Jacquet | first1=H. | last2=Langlands | first2=Robert P. | title=Automorphic forms on GL(2) | url=http://www.sunsite.ubc.ca/DigitalMathArchive/Langlands/JL.html#book | publisher=[[Springer-Verlag]] | location=Berlin, New York | series=Lecture Notes in Mathematics, Vol. 114 | doi=10.1007/BFb0058988 | mr=0401654 | year=1970 | volume=114 | isbn=978-3-540-04903-6}} | |||
*J. A. Shalika, ''The multiplicity one theorem for <math>GL_n</math>'', The Annals of Mathematics, 2nd. Ser., Vol. 100, No. 2 (1974), 171-193. | |||
[[Category:Representation theory]] | |||
[[Category:Automorphic forms]] |
Revision as of 01:13, 2 February 2014
In representation theory, a branch of mathematics, the Whittaker model is a realization of a representation of a reductive algebraic group such as GL2 over a finite or local or global field on a space of functions on the group. It is named after E. T. Whittaker even though he never worked in this area, because Template:Harvs pointed out that for the group SL2(R) some of the functions involved in the representation are Whittaker functions.
Irreducible representations without a Whittaker model are sometimes called "degenerate", and those with a Whittaker model are sometimes called "generic". The representation θ10 of the symplectic group Sp4 is the simplest example of a degenerate representation.
Whittaker models for GL2
If G is the algebraic group GL2 and F is a local field, and τ is a fixed non-trivial character of the additive group of F and π is an irreducible representation of G(F), then the Whittaker model for π is a representation π on a space of functions f on G(F) satisfying
Template:Harvtxt used Whittaker models to assign L-functions to admissible representations of GL2.
Whittaker models for GLn
Let be the general linear group , a smooth complex valued non-trivial additive character of and the subgroup of consisting of unipotent upper triangular matrices. A non-degenerate character on is of the form
for ∈ and non-zero , ..., ∈ . If is a smooth representation of , a Whittaker functional is a continuous linear functional on such that for all ∈ , ∈ . Multiplicity one states that, for unitary irreducible, the space of Whittaker functionals has dimension at most equal to one.
Whittaker models for reductive groups
If G is a split reductive group and U is the unipotent radical of a Borel subgroup B, then a Whittaker model for a representation is an embedding of it into the induced (Gelfand–Graev) representation IndTemplate:Su(χ), where χ is a non-degenerate character of U.
See also
- Gelfand–Graev representation, roughly the sum of Whittaker models over a finite field.
- Kirillov model
References
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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
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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.
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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