Qualitative spatial and temporal reasoning problems are usually expressed in terms of constraint satisfaction problems, with determining consistency as the main reasoning problem. Because of the high complexity of determining consistency, several notions of local consistency, such as path-consistency, k-consistency and corresponding algorithms have been introduced in the constraint community an...

— A model of a stationary universe is proposed. In this framework, time is defined as a local and quantum-mechanical notion in the sense that it is defined for each local and quantum-mechanical system consisting of finite number of particles. The total universe consisting of infinite number of particles has no time associated. It is a stationary bound state of the total Hamiltonian of infinite ...