Syntactic congruences and syntactic algebras

Syntactic Congruences and Syntactic Algebras

Standard topological algebras: syntactic and principal congruences and profiniteness

A topological quasi-variety Q T ∼ ) := IScP + ∼ generated by a finite algebra ∼ with the discrete topology is said to be standard if it admits a canonical axiomatic description. Drawing on the formal language notion of syntactic congruences, we prove that Q T ∼ ) is standard provided that the algebraic quasi-variety generated by ∼ is a variety, and that syntactic congruences in that variety are...

On Syntactic Congruences for ω−languages∗

In this paper we investigate several questions related to syntactic congruences and to minimal automata associated with ω-languages. In particular we investigate relationships between the so-called simple (because it is a simple translation from the usual definition in the case of finitary languages) syntactic congruence and its infinitary refinement (the iteration congruence) investigated by A...

Principal and Syntactic Congruences in Congruence-distributive and Congruence-permutable Varieties

We give a new proof that a finitely generated congruence-distributive variety has finitely determined syntactic congruences (or equivalently, term finite principal congruences), and show that the same does not hold for finitely generated congruence-permutable varieties, even under the additional assumption that the variety is residually very finite. 2000 Mathematics subject classification: 08B10.

Syntactic and pseudo-syntactic approaches for text retrieval

We study how the use of syntactic information can improve the performance of Information Retrieval systems based on single-word terms. We consider two different approaches. The first one identifies the syntactic structure of the text by means of a shallow parser in order to extract the head-modifier pairs of the most relevant syntactic dependencies, which are used as complex