منابع مشابه
Cobham's theorem for substitutions
The seminal theorem of Cobham has given rise during the last 40 years to a lot of works around non-standard numeration systems and has been extended to many contexts. In this paper, as a result of fifteen years of improvements, we obtain a complete and general version for the so-called substitutive sequences. Let α and β be two multiplicatively independent Perron numbers. Then, a sequence x ∈ A...
متن کاملAn Abstract Factorization Theorem for Explicit Substitutions
We study a simple form of standardization, here called factorization, for explicit substitutions calculi, i.e. lambda-calculi where beta-reduction is decomposed in various rules. These calculi, despite being non-terminating and non-orthogonal, have a key feature: each rule terminates when considered separately. It is well-known that the study of rewriting properties simplifies in presence of te...
متن کاملDecomposition theorem for invertible substitutions on three - letter alphabet ∗
We study the structure of invertible substitutions on three-letter alphabet. We show that there exists a finite set S of invertible substitutions such that any invertible substitution can be written as Iw ◦ σ1 ◦ σ2 ◦ · · · ◦ σk, where Iw is the inner automorphism associated with w, and σj ∈ S for 1 ≤ j ≤ k. As a consequence, M is the matrix of an invertible substitution if and only if it is a f...
متن کاملA theorem of Cobham for non-primitive substitutions
Given a subset E of N = {0, 1, 2, · · · } can we find an elementary algorithm (i.e., a finite state automaton) which accepts the elements of E and rejects those that do not belong to E? In 1969 A. Cobham showed that the existence of such an algorithm deeply depends on the numeration base. He stated [Co1]: Let p and q be two multiplicatively independent integers (i.e., p 6= q for all integers k,...
متن کاملGENERALIZED PRINCIPAL IDEAL THEOREM FOR MODULES
The Generalized Principal Ideal Theorem is one of the cornerstones of dimension theory for Noetherian rings. For an R-module M, we identify certain submodules of M that play a role analogous to that of prime ideals in the ring R. Using this definition, we extend the Generalized Principal Ideal Theorem to modules.
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ژورنال
عنوان ژورنال: Journal of the European Mathematical Society
سال: 2011
ISSN: 1435-9855
DOI: 10.4171/jems/294