The Space Groups of Two Dimensional Minkowski Space

1978 ◽  
Vol 30 (5) ◽  
pp. 1103-1120
Author(s):  
George Maxwell

LetEbe an n-dimensional real affine space,Vits vector space of translations andA(E)the affine group ofE.Suppose that (. , .) is a nondegenerate symmetric bilinear form on F of signature(n —1, 1), O(V) its orthogonal group andS(V)its group of similarities.

1988 ◽  
Vol 211 (1-2) ◽  
pp. 107-110 ◽  
Author(s):  
D. Cangemi ◽  
M. Makowka ◽  
G. Wanders

Author(s):  
George Maxwell

Let V be the vector space of translations of a finite dimensional real affine space. The principal aim of this paper is to study (generally non-Euclidean) space groups whose point groups K are ‘linear’ Coxeter groups in the sense of Vinberg (4). This involves the investigation of lattices Λ in V left invariant by K and the calculation of cohomology groups H1(K, V/Λ) (3). The first problem is solved by generalizing classical concepts of ‘bases’ of root systems and their ‘weights’, while the second is carried out completely in the case when the Coxeter graph Γ of K contains only edges marked by 3. An important part in the calculation of H1(K, V/Λ) is then played by certain subgraphs of Γ which are complete multipartite graphs. The only subgraphs of this kind which correspond to finite Coxeter groups are of type Al× … × A1, A2, A3 or D4. This may help to explain why, in our earlier work on space groups with finite Coxeter point groups (3), (2), components of r belonging to these types played a rather mysterious exceptional role.


1991 ◽  
Vol 06 (29) ◽  
pp. 5215-5229 ◽  
Author(s):  
A. STERN

We study n=1 supergravity written on a two-dimensional disc (× time) in the absence of any sources. The dynamics of the boundary of the disc is equivalent to that of a superstring in (2+1)-dimensional Minkowski space. The relevant current algebra for the theory corresponds to the central extension of the super-Poincaré loop group. We find unitary representations of the current algebra by applying both a highest weight state construction and the method of induced representations.


1958 ◽  
Vol 1 (3) ◽  
pp. 180-180
Author(s):  
Jonathan Wild

Given a vector space V = {x, y, ...} over an arbitrary field. In V a symmetric bilinear form (x,y) i s given. A subspace W is called totally isotropic [t.i.] if (x,y) = 0 for every pair x W, y W.Let Vn and Vm be two t.i. subspaces of V; n < m. Lower indices always indicate dimensions. It is a well known and fundamental fact of analytic geometry that there exists a t.i. subspace Wm of V containing Vn [cf. Dieudonné: Les Groupes classiques , P. 18]. As no simple direct proof seems to be available, we propose to supply one.


Author(s):  
Jean-Michel Bismut

This chapter recalls various results on Clifford algebras and Heisenberg algebras. It first introduces the Clifford algebra of a vector space V equipped with a symmetric bilinear form B and then specializes the construction of the Clifford algebra to the case of V ⊕ V*. Next, the chapter argues that, if (V,ω‎) is a symplectic vector space, then the associated Heisenberg algebra is constructed and then specialized to the case of V ⊕ V*. Hereafter, the chapter considers the combination of the Clifford and Heisenberg algebras for V ⊕ V*, and constructs the complex Λ‎· (V*) ⊗ S· (V*), ̄ƌ) which is the subcomplex of polynomial forms in the de Rham complex. Finally, when V is equipped with a scalar product, this complex is related to a Witten complex over V.


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