Describing morphological phenomena of modern greek using a unification grammar formalism

The unification-based formalism, suitable for encoding a wide variety of grammars for computational applications and the linguistic research, can also be applied to the area of computational morphology. The morphological processor, presented in this paper, is based on the PATR II formalism and provides the system with a context-sensitive approach as opposed to the more classical finite state automaton approach. It has been designed as a tool to describe a range of linguistic models, in which unification plays the centrol role. Our software system can be used to describe various morphological phenomena of Modern Greek (and any other highly inflected language) such as inflection, derivation, accentuation, composition, etc. Stored morphological information representing a word, is operationally divided into syntactic and semantic parts and is described in terms of attribute-value pairs. The unification-based formalism provides a unified approach to deal with the stratified levels of linguistic information, namely morphology, syntax and semantics.     

A description of the effect of short range ordering in the compound energy formalism

The current state of the compound energy formalism (CEF) to model ordering and the technique to handle short range ordering (SRO) were discussed. Although there are some methods which allow better treatment for SRO, such as the cluster variation method (CVM) or the Monte Carlo method (MC), these methods are difficult to handle in multi-component systems because of their complexity. In the compound energy formalism, SRO is not explicitly described. However it is possible to take the contribution of SRO to the Gibbs free energy into account through the reciprocal parameter, which has the same concentration dependency as ΔG_m^SRO. Introducing the reciprocal parameter of the form, L_i,j:i,j for the two sublattice model and L_{i,j:i,j:^*:^*} for the four sublattice model, one can satisfactorily describe the contribution of SRO to the Gibbs free energy in the CEF.     

Implementation of a Modelica compiler using JastAdd attribute grammars

We have implemented a compiler for key parts of Modelica, an object-oriented language supporting equation-based modeling and simulation of complex physical systems. The compiler is extensible, to support experiments with emerging tools for physical models. To achieve extensibility, the implementation is done declaratively in JastAdd, a metacompilation system supporting modern attribute grammar mechanisms such as reference attributes and nonterminal attributes.This paper reports on experiences from this implementation. For name and type analyses, we illustrate how declarative design strategies, originally developed for a Java compiler, could be reused to support Modelica’s advanced features of multiple inheritance and structural subtyping. Furthermore, we present new general design strategies for declarative generation of target ASTs from source ASTs. We illustrate how these strategies are used to resolve a generics-like feature of Modelica called modifications, and to support flattening, a fundamental part of Modelica compilation. To validate that the approach is practical, we have compared the execution speed of our compiler to two existing Modelica compilers.     

A method for computation of the discrete Fourier transform over a finite field

The discrete Fourier transform over a finite field finds applications in algebraic coding theory. The proposed computation method for the discrete Fourier transform is based on factorizing the transform matrix into a product of a binary block circulant matrix and a diagonal block circulant matrix.     

A finite element analysis of flow over a backward facing step

The finite element method is used to solve both laminar and turbulent flow over a downstream facing step with a one equation model used for the turblent flow analysis. The effect of using upwind elements is investigated and the results are compared with published experimental and numerical data.     

Hyper-arc consistency of polynomial constraints over finite domains using the modified Bernstein form

This paper describes an algorithm to enforce hyper-arc consistency of polynomial constraints defined over finite domains. First, the paper describes the language of so called polynomial constraints over finite domains, and it introduces a canonical form for such constraints. Then, the canonical form is used to transform the problem of testing the satisfiability of a constraint in a box into the problem of studying the sign of a related polynomial function in the same box, a problem which is effectively solved by using the modified Bernstein form of polynomials. The modified Bernstein form of polynomials is briefly discussed, and the proposed hyper-arc consistency algorithm is finally detailed. The proposed algorithm is a subdivision procedure which, starting from an initial approximation of the domains of variables, removes values from domains to enforce hyper-arc consistency.     

The semiring of matrices over a finite chain

Let L_m denote the chain {0,1,2,…,m-1} with the usual ordering and M_n(L_m) the matrix semiring of all n×n matrices with elements in L_m. We firstly introduce some order-preserving semiring homomorphisms from M_n(L_m) to M(L_k). By using these homomorphisms, we show that a matrix over the finite chain L_m can be decomposed into the sum of some matrices over the finite chain L_k, where k<m. As a result, cut matrices decomposition theorem of a fuzzy matrix (Theorem 4 in [Z.T. Fan, Q.S. Cheng, A survey on the powers of fuzzy matrices and FBAMs, International Journal of Computational Cognition 2 (2004) 1-25 (invited paper)]) is generalized and extended. Further, we study the index and periodicity of a matrix over a finite chain and get some new results. On the other hand, we introduce a semiring embedding mapping from the semiring M_n(L_m) to the direct product of the h copies of the semiring M_n(L_k) and discuss Green’s relations on the multiplicative semigroup of the semiring M_n(L_m). We think that some results obtained in this paper is useful for the study of fuzzy matrices.     

Some subsets of automata over a finite ring

Sets of Mealy and Moore automata over an arbitrary finite commutative-associative ring are investigated in which transition and output functions are linear combinations of functions of automaton states and functions of inputs. Subsets of strongly connected, reduced, and reversible automata and automata with permutation transition functions are characterized.     

On the complexity of analysis of automata over a finite ring

A general scheme is investigated that is destined for obtaining estimates based on the cardinality of subsets of a fixed set of automata over some finite commutative-associative ring with unit element. A scheme is proposed to solve parametric systems of polynomial equations based on classes of associated elements of the ring. Some general characteristics of automata over the ring are established.     

Two types of nonlinear automata over a finite ring

The structure of a class of automata is analyzed. These automata are analogs of symmetric chaotic dynamical systems over a finite ring, namely, the Guckenheimer–Holmes cycle and free-running systems. Problems of parametric identification and identification of initial states are solved, and a set of fixed points of automaton mappings is characterized. Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 57–68, July–August 2009.