A new method for solving some hard combinatorial optimization problems is suggested, admitting a certain reformulation. Considering such a problem, several different similar problems are prepared which have the same set of solutions. They are solved on computer in parallel until one of them will be solved, and that solution is accepted. Notwithstanding the evident overhead, the whole run-time c...

The conformal formulation provides a method for constructing and parametrizing solutions of the Einstein constraint equations by mapping freely chosen sets of conformal data to solutions, provided a certain set of coupled, elliptic determined PDEs (whose expression depends on the chosen conformal data) admit a unique solution. For constant mean curvature (CMC) data, it is known in almost all ca...

Application-led research is vitally important – applications provide designers and developers of ubiquitous computing systems with requirements, drive progress towards solutions, validate technology and provide insights into technology use. They offer the chance to demonstrate the usefulness of complex systems components that might otherwise be difficult to appreciate and they are, of course, i...

Covariant-contravariant simulation is a combination of standard (covariant) simulation, its contravariant counterpart and bisimulation. We have previously studied its logical characterization by means of the covariant-contravariant modal logic. Moreover, we have investigated the relationships between this model and that of modal transition systems, where two kinds of transitions (the so-called ...

In this paper, we show that some five-dimensional rotating black hole solutions of both gauged and ungauged supergravity, with independent rotation parameters and three charges admit separable solutions to the massless Hamilton-Jacobi and Klein-Gordon equations. This allows us to write down a conformal Killing tensor for the spacetime. Conformal Killing tensors obey an equation involving a co-v...

The concept of the derivative-dependent functional separable solution, as a generalization to the functional separable solution, is proposed. As an application, it is used to discuss the generalized nonlinear diffusion equations based on the generalized conditional symmetry approach. As a consequence, a complete list of canonical forms for such equations which admit the derivative-dependent fun...

Forgetting, in description logic, is a non-standard reasoning technique. The aim of this technique is to eliminate concept and role symbols from a knowledge base, whilst preserving all logical consequences up to the remaining symbols. In this research, three forgetting tools were used to understand the relationship between the approaches on which they are based: SCAN, LETHE and FAME. The approa...

An algebraic method for a general construction of intersecting p-brane solutions in diverse spacetime dimensions is discussed. An incidence matrix describing configurations of electric and magnetic fields is introduced. Intersecting p-branes are specified by solutions of a system of characteristic algebraic equations for the incidence matrix. This set of characteristic equations generalizes a s...

In this paper we give a partial answer to a 1980 question of Lazslo Babai: “Which [finite] groups admit an oriented graph as a DRR?” That is, which finite groups admit an oriented regular representation (ORR)? We show that every finite non-solvable group admits an ORR, and provide a tool that may prove useful in showing that some families of finite solvable groups admit ORRs. We also completely...