In the lectures given at ’96 Kashikojima Summer Institute, Amagi-Highland Seminars, and Yukawa Institute Workshop, the old-fashioned dualities and the theory of extended objects are reviewed, starting from ’t Hooft-Mandelstam duality and following the author’s old works. Application of the old-fashioned dualities to new issues are also given on the D-branes, on the phase transition of B-F theor...

We present an algebraic treatment of the correspondence of gaps and dualities in partial ordered classes induced by the morphism structures of certain categories which we call Heyting (such are for instance all cartesian closed categories, but there are other important examples). This allows to extend the results of [14] to a wide range of more general structures. Also, we introduce a notion of...

In this paper we show duality results between categories of equations and categories of coequations. These dualities are obtained as restrictions of dualities between categories of algebras and coalgebras, which arise by lifting contravariant adjunctions on the base categories. By extending this approach to (co)algebras for (co)monads, we retrieve the duality between equations and coequations f...

Abstract: Infinite–dimensional linear dynamic systems described by infinite matrices are studied. Approximate controllability for systems with lower-diagonal matrices is investigated, whereas observability is studied for systems with row-finite and upper-diagonal matrices. Different necessary or sufficient conditions of approximate controllability and observability of such systems are given. Th...

Let be the Laplace-d'Alembert operator on a pseudo-Riemannian manifold (M; g). We derive a series expansion for the fundamental solution G(x; y) of + H , H 2 C 1 (M), which behaves well under various symmetric space dualities. The qualitative properties of this expansion were used in our paper in Invent. Math. 129 (1997) 63{74, to show that the property of vanishing logarithmic term for G(x; y)...

We study the Howe dualities involving the reductive dual pairs (O(d), spo(2m|2n)) and (Sp(d), osp(2m|2n)) on the (super)symmetric tensor of C ⊗ C. We obtain complete decompositions of this space with respect to their respective joint actions. We also use these dualities to derive a character formula for these irreducible representations of spo(2m|2n) and osp(2m|2n) that appear in these decompos...

We set up a framework that subsumes many important dualities in mathematics (Birkhoff, Stone, Priestly, Baker-Beynon, etc.) as well as the classical correspondence between polynomial ideals and affine varieties in algebraic geometry. Our main theorems provide a generalisation of Hilbert’s Nullstellensatz to any (possibly infinitary) variety of algebras. The common core of the above dualities be...

This paper summarizes the description of the statics and velocity kinematics of serial, parallel and mobile robots, based on the fundamental concepts of twists and wrenches, reciprocity, the “selectively non-reciprocal screw,” and “kinematic dualities.” This approach leads to a simplified since unified treatment of serial, parallel and mobile robot kinematics (which robotics textbooks lack) and...

Dualities such as self versus other, good versus bad, and in-group versus out-group are pervasive features of human experience, structuring the majority of cognitive and affective processes. Yet, an entirely different way of experiencing, one in which such dualities are relaxed rather than fortified, is also available. It depends on recognizing, within the stream of our consciousness, the nondu...

During the last decade, intriguing dualities between gauge and string theory have been found and explored. They provide a novel window on strongly coupled gauge physics, including QCD-like models. Based on a short historical review of modern string theory, we shall explain how so-called AdS/CFT dualities emerged at the end of the 1990s. Some of their concrete implications and remarkable recent ...