valdis laan in [5] introduced an extension of strong flatness which is called weak pullback flatness. in this paper we introduce a new property of acts over monoids, called u-wpf which is an extension of weak pullback flatness and give a classification of monoids by this property of their acts and also a classification of monoids when this property of acts implies others. we also show that regu...

We show that the classical strong maximum principle, concerning positive supersolutions of linear elliptic equations vanishing on boundary domain $ \Omega can be extended, under suitable conditions, to case in which forcing term f(x) is changing sign. In addition, for solutions normal derivative may also vanish (definition flat solutions). This leads examples unique continuation property fails....

Let n > 1 and G be the group SU(n) or Sp(n). This paper constructs compact symplectic manifolds whose symplectic quotient under a Hamiltonian G-action does not inherit the strong Lefschetz property .

Let P be a monotone increasing graph property, let G = (V,E) be a graph, and let q be a positive integer. In this paper, we study the (1 : q) Maker-Breaker game, played on the edges of G, in which Maker’s goal is to build a graph that satisfies the property P . It is clear that in order for Maker to have a chance of winning, G itself must satisfy P . We prove that if G satisfies P in some stron...

A group signature allow any member of a group to sign on behalf of the group. A group blind signature requires that a group member signs on group’s behalf a document without knowing its content. In this paper we propose a practical coalition-resistant group blind signature scheme based on the strong RSA and the decisional Diffie-Hellman assumptions. Our scheme is an extension of the group signa...

The problem of the sample variance computation for epistemic inter-val-valued data is, in general, NP-hard. Therefore, known efficient algorithms for computing variance require strong restrictions on admissible intervals like the no-subset property or heavy limitations on the number of possible intersections between intervals. A new asymptotic algorithm for computing the upper bound of the samp...