The notion of a scalar equation describing pseudo-spherical surfaces is reviewed. It is shown that if an equation admits this structure, the existence of conservation laws, symmetries, and quadratic pseudo-potentials, can be studied by geometrical means. As an application, it is pointed out that the important Camassa–Holm and Hunter–Saxton equations possess features considered to be characteris...

Characterizations of fuzzy ideals of a pseudo-BCH-algebra are established. Conditions for a fuzzy set to be a fuzzy ideal are given. The homomorphic properties of fuzzy ideals are provided. Finally, characterizations of Noetherian pseudo-BCH-algebras and Artinian pseudoBCH-algebras via fuzzy ideals are obtained. Mathematics Subject Classi…cation: 03G25, 06F35.

In this paper we use continuous family of multisections of the moduli space of pseudo holomorphic discs to partially improve the construction of Lagrangian Floer cohomology of [13] in the case of R coefficient. Namely we associate cyclically symmetric filtered A∞ algebra to every relatively spin Lagrangian submanifold. We use the same trick to construct a local rigid analytic family of filtered...

In the late 1980s, Graeme Segal axiomatized conformal field theory in terms of a cobordism category. In that same preprint he outlined a more symmetric trace approach, which was recently rigorized in terms of pseudo algebras over a 2-theory. In this paper, we treat the cobordism approach in the pseudo algebra context. We introduce a new algebraic structure on a bicategory, called a pseudo 2-alg...

An implementation of the algebra of pseudo diierential operators in the computer algebra system AXIOM is described. In several examples the application of the package to typical computations in the theory of integrable systems is demonstrated. Nature of physical problem: Generation of integrable systems solvable by the Inverse Scattering Method and determination of conservation laws Method of s...

This article provides a complete description of the differential Gerstenhaber algebras of all nilpotent complex structures on any real six-dimensional nilpotent algebra. As an application, we classify all pseudo-Kählerian complex structures on six-dimensional nilpotent algebras such that the differential Gerstenhaber algebra of its complex structure is quasi-isomorphic to that of its symplectic...

We show that it is NP-hard to decide if a geometric graph can be extended to a pseudo-triangulation by adding lines and not violating a given degree bound. The equivalent problem for triangulations is known to be NP-hard if we ask for a triangulation with maximum vertex degree 7 [3]. We show that finding a pseudotriangulations is already NP-complete if we forbid vertex degrees greater than 5. T...