Let G be a real semisimple Lie group. Let g0 be the Lie algebra of G. We will denote the complexification of any vector space V0 by V and its dual by V ∗. Let g0 = k0 + p0 be a fixed Cartan decomposition corresponding to the Cartan involution θ of g0. Let K be the corresponding maximal compact subgroup of G. Let us fix T ⊂ K a maximal torus. Define S ⊂ t∗ as the set of weights of T that are sum...

In this paper we take steps towards the development of a robust stabilization theory for nonlinear plants. An approach using the left coprime factorization of the plant and controller under certain differential boundedness assumptions is used. We first foeus attention on a characterization of the class of all stabilizing nonlinear controllers K~ for a nonlinear plant G, parameterized in terms o...

Tutte observed that every nowhere-zero k-flow on a plane graph gives rise to a kvertex-coloring of its dual, and vice versa. Thus nowhere-zero integer flow and graph coloring can be viewed as dual concepts. Jaeger further shows that if a graph G has a face-k-colorable 2-cell embedding in some orientable surface, then it has a nowhere-zero k-flow. However, if the surface is nonorientable, then a...

In this paper, we introduce a new algorithm ConSubg(k, G) for computing all the connected subgraphs of a fixed size k of a graph G. ConSubg exploits the structure of the graph to prevent the generation of disconnected subgraphs, and is thus particularly advantageous for large sparse graphs. The two main features of our approach are the construction of a combination tree and the definition of an...

Part I proved that for every quasivariety K of structures (which may have both operations and relations) there is a semilattice S with operators such that the lattice of quasiequational theories of K (the dual of the lattice of sub-quasivarieties of K) is isomorphic to Con(S,+, 0,F). It is known that if S is a join semilattice with 0 (and no operators), then there is a quasivariety Q such that ...

Tutte observed that every nowhere-zero k-flow on a plane graph gives rise to a kvertex-coloring of its dual, and vice versa. Thus nowhere-zero integer flow and graph coloring can be viewed as dual concepts. Jaeger further shows that if a graph G has a face-k-colorable 2-cell embedding in some orientable surface, then it has a nowhere-zero k-flow. However, if the surface is nonorientable, then a...

1.1. Geometry. A covariant derivative on a manifold M is an operator ∇XY on vector fields X and Y satisfying for any smooth function f : (i) ∇fXY = f∇XY ; and (ii) ∇X(fY ) = f∇XY + (∇Xf)Y . If g is a Riemannian metric on M , then there is associated with g a unique covariant derivative ∇ characterized by: (iii) ∇XY −∇YX = [X,Y ]; and (iv) ∇X ( g(Y,Z) ) = g(∇XY, Z) + g(Y,∇XZ). We define the Chri...

We prove the existence of a strict deformation quantization for the canonical Poisson structure on the dual of an integrable Lie algebroid. It follows that any Lie groupoid C-algebra may be regarded as a result of a quantization procedure. The C-algebra of the tangent groupoid of a given Lie groupoid G (with Lie algebra G) is the C-algebra of a continuous field of C-algebras over R with fibers ...

CLASS FIELD THEORY: CLASS FORMATIONS Tate’s theorem (see (4) above) shows that, in order to have a class field theory over a field k, all one needs is, for each system of fields ksep L K k; ŒLWk <1; L=K Galois, a G.L=K/-module CL and a “fundamental class” uL=K 2 H .G.L=K/;CL/ satisfying Tate’s hypotheses; the pairs .CL;uL=K/ should also satisfy certain natural conditions when K and L vary. The...