On some factorization problems

On some factorization problems

We consider three notions of factorization arising in different frameworks: factorizing languages, factorization of the natural numbers, factorizing codes. A language X ⊆ A∗ is called factorizing if there exists a language Y ⊆ A∗ such that XY = A∗ and the product is unambiguous. This is a decidable property for recognizable languages X . If we consider the particular case of unary alphabets, we...

global results on some nonlinear partial differential equations for direct and inverse problems

در این رساله به بررسی رفتار جواب های رده ای از معادلات دیفرانسیل با مشتقات جزیی در دامنه های کراندار می پردازیم . این معادلات به فرم نیم-خطی و غیر خطی برای مسایل مستقیم و معکوس مورد مطالعه قرار می گیرند . به ویژه، تاثیر شرایط مختلف فیزیکی را در مساله، نظیر وجود موانع و منابع، پراکندگی و چسبندگی در معادلات موج و گرما بررسی می کنیم و به دنبال شرایطی می گردیم که متضمن وجود سراسری یا عدم وجود سراسر...

Commcnts on Some Problems

Some Metrical Problems on S "

We present some problems related to right(or bi-)invariant metrics d on the symmetric group of permutations S,. Characterizations and constructions of bi-invariant extremal (in the corresponding convex cone) metrics are given, esp. for n 6 5 . We also consider special subspaces of the metric space (S,,, d ) : unit balls, sets with prescribed distances (L-cliques), "hamiltonian" sets. Here we gi...

Some Problems on Graphic Sequences

A nonnegative integer sequence π is graphic if there is some simple graph G having degree sequence π. In that case, G is said to realize or be a realization of π. A given degree sequence may have many realizations, and it has been of interest to examine the spectrum of properties and parameters that occur across these realizations. In this survey, we present five areas of recent research on gra...