An interactive state monad example

A common problem among information systems is the storage and maintenance of permanent information identified by a key. Such systems are typically known as data base engines or simply as data bases. Today the systems information market is full of solutions that provide mass storage capacities implemented in different operating system and with great amounts of extra functionalities. In this paper we will focus on the formal high level specification of data base systems in the Haskell language. We begin by introducing a high level view of a data base system with a specification of the most common operations in a functional point of view. We then augment this specification by lifting to the state monad which is then modified once again to permit input/output operations between the computations

Critical behavior of a three-dimensional hardcore-cylinder composite system

In this work the critical indices β, γ , and ν for a three-dimensional (3D) hardcore cylinder composite system with short-range interaction have been obtained. In contrast to the 2D stick system and the 3D hardcore cylinder system, the determined critical exponents do not belong to the same universality class as the lattice percolation,although they obey the common hyperscaling relation for a 3D system. It is observed that the value of the correlation length exponent is compatible with the predictions of the mean field theory. It is also shown that, by using the Alexander-Orbach conjuncture, the relation between the conductivity and the correlation length critical exponents has a typical value for a 3D lattice system.