commutative properties of four-dimensional generalized symmetric pseudo-riemannian manifolds were considered. specially, in this paper, we studied skew-tsankov and jacobi-tsankov conditions in 4-dimensional pseudo-riemannian generalized symmetric manifolds.

Research and development of lead-free piezoelectric materials are still the hottest topics in the field of piezoelectricity. One of the most promising lead-free family of compounds to replace lead zirconate-titanate for actuators is that of Bi0.50Na0.50TiO₃ (BNT) based solid solutions. The pseudo-binary (1 - x)Bi0.50Na0.50TiO₃-xBa1 - yCayTiO₃ system has been proposed for high temperature capaci...

A new format for solid-phase immunoassays has been developed in which a monoclonal antibody-coated membrane, incorporated into a cylindrical, disposable device, regulates sample and reagent delivery. We illustrate the method with a two-site, immunoenzymometnc assay that can detect human choriogonadotropin at less than 50 mt. units/L (4 pg/L) in urine and less than 25 mt. units/L (2 j.tg/L) in s...

From a pseudo-triangulation with n tetrahedra T of an arbitrary closed orientable connected 3-manifold (for short, a 3D-space) M, we present a gem J , inducing S, with the following characteristics: (a) its number of vertices is O(n); (b) it has a set of p pairwise disjoint couples of vertices {ui, vi}, each named a twistor; (c) in the dual (J ) of J ′ a twistor becomes a pair of tetrahedra wit...

In this paper, we introduce the notion of hyper pseudo B C K - algebras, which is a generalization of pseudo BCK -algebras and hyper BCK -algebras and we investigates some related properties. In follow, we de ne some kinds of hyper pseudo BCK -ideals of a hyper pseudo BCK - algebra and we find the relations among them. Finally, we characterize the hyper pseudo BCK -ideals of type 4 generated by...

In this paper we study particular classes of pseudo-BCK algebras, bounded or not bounded, as pseudo-BCK(pP) algebras, pseudo-BCK(pP) lattices, pseudo-Hájek(pP) algebras and pseudo-Wajsberg algebras. We introduce new classes of pseudo-BCK(pP) lattices, we establish hierarchies and we give some examples. We work with left-defined algebras and we work with → and ; as primitive operations, not with...