New algorithms for deciding the injectivit y of the global update funct ion associat ed with a cellular automaton C A of dimension one are presented. This is done by interpreting each ordered pair dete rmined by the local update function as th e edge of a labeled directed graph GR which has the prope rty that each bi-infinite sequence of states of the cellular automaton is th e sequence of inpu...

— The paper is devote d to the finit e element analysis of second order e Hipt ie eigenvalue problems in the case when the approximate domains Oh are not subdomains of the original domain fl a U. The considérations are restricted to piecewise linear approximations and in the case of eigenfunctions to simple eigenvalues. The optimum rates of convergence for hoth the approximate eigenvalues and t...

Traditionally, invariant assertions are used to verify the partial correctness of while loops with respect to pre/post specifications. In this paper we discuss a related but distinct concept, namely invariant relations, and show how invariant relations are a more potent tool in the analysis of while loops: whereas invariant assertions can only be used to prove partial correctness, invariant rel...

A bst ract. A one-dimensional cellular automaton rule with specified boundary conditions can be considered as acting simultaneously on all finite lattices, which gives a mapping between formal languages. Regular lang uages are always mapped to regular langu ages, contex t-free to context-free, context-sensitive to context-sensitive, and recursive sets to recursive sets . In particular, the fini...

1Landau Associates, 130 2nd Ave South, Edmonds, WA 98020, U.S.A. 2Civil and Environmental Engineering and National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 205 North Mathews Ave Urbana, IL 61801, U.S.A. 3Department of Nuclear, Plasma and Radiological Engineering, University of Illinois at Urbana-Champaign, 216 Talbot Lab, 104 S. Wright St., Urbana, IL ...

For a plane polygonal domain Q and a corresponding (general) triangulation we define classes of functions pmix, v) which are polynomials on each triangle and which are in C^'CQ) and also belong to the Sobolev space ^""^'(n). Approximation theoretic properties are proved concerning these functions. These results are then applied to the approximate solution of arbitrary-order elliptic boundary va...

The fundamental theory of crystal twinning has been long established, leading to a significant advance in understanding the nature of this physical phenomenon. However, there remains a substantial gap between the elaborate theory and the practical determination of twinning elements. This paper proposes a direct and simple method - valid for any crystal structure and based on the minimum shear c...