90 research outputs found
Evolving MultiAlgebras unify all usual sequential computation models
It is well-known that Abstract State Machines (ASMs) can simulate
"step-by-step" any type of machines (Turing machines, RAMs, etc.). We aim to
overcome two facts: 1) simulation is not identification, 2) the ASMs simulating
machines of some type do not constitute a natural class among all ASMs. We
modify Gurevich's notion of ASM to that of EMA ("Evolving MultiAlgebra") by
replacing the program (which is a syntactic object) by a semantic object: a
functional which has to be very simply definable over the static part of the
ASM. We prove that very natural classes of EMAs correspond via "literal
identifications" to slight extensions of the usual machine models and also to
grammar models. Though we modify these models, we keep their computation
approach: only some contingencies are modified. Thus, EMAs appear as the
mathematical model unifying all kinds of sequential computation paradigms.Comment: 12 pages, Symposium on Theoretical Aspects of Computer Scienc
Kolmogorov Complexity in perspective. Part I: Information Theory and Randomnes
We survey diverse approaches to the notion of information: from Shannon
entropy to Kolmogorov complexity. Two of the main applications of Kolmogorov
complexity are presented: randomness and classification. The survey is divided
in two parts in the same volume. Part I is dedicated to information theory and
the mathematical formalization of randomness based on Kolmogorov complexity.
This last application goes back to the 60's and 70's with the work of
Martin-L\"of, Schnorr, Chaitin, Levin, and has gained new impetus in the last
years.Comment: 40 page
Kolmogorov complexity in perspective
We survey the diverse approaches to the notion of information content: from
Shannon entropy to Kolmogorov complexity. The main applications of Kolmogorov
complexity are presented namely, the mathematical notion of randomness (which
goes back to the 60's with the work of Martin-Lof, Schnorr, Chaitin, Levin),
and classification, which is a recent idea with provocative implementation by
Vitanyi and Cilibrasi.Comment: 37 page
Refinment of the "up to a constant" ordering using contructive co-immunity and alike. Application to the Min/Max hierarchy of Kolmogorov complexities
We introduce orderings between total functions f,g: N -> N which refine the
pointwise "up to a constant" ordering <=cte and also insure that f(x) is often
much less thang(x). With such orderings, we prove a strong hierarchy theorem
for Kolmogorov complexities obtained with jump oracles and/or Max or Min of
partial recursive functions. We introduce a notion of second order conditional
Kolmogorov complexity which yields a uniform bound for the "up to a constant"
comparisons involved in the hierarchy theorem.Comment: 41 page
Set theoretical Representations of Integers, I
We reconsider some classical natural semantics of integers (namely iterators
of functions, cardinals of sets, index of equivalence relations), in the
perspective of Kolmogorov complexity. To each such semantics one can attach a
simple representation of integers that we suitably effectivize in order to
develop an associated Kolmogorov theory. Such effectivizations are particular
instances of a general notion of "self-enumerated system" that we introduce in
this paper. Our main result asserts that, with such effectivizations,
Kolmogorov theory allows to quantitatively distinguish the underlying
semantics. We characterize the families obtained by such effectivizations and
prove that the associated Kolmogorov complexities constitute a hierarchy which
coincides with that of Kolmogorov complexities defined via jump oracles and/or
infinite computations. This contrasts with the well-known fact that usual
Kolmogorov complexity does not depend (up to a constant) on the chosen
arithmetic representation of integers, let it be in any base unary, binary et
so on. Also, in a conceptual point of view, our result can be seen as a mean to
measure the degree of abstraction of these diverse semantics.Comment: 56 page
The algebra of binary trees is affine complete
A function on an algebra is congruence preserving if, for any congruence, it
maps pairs of congruent elements onto pairs of congruent elements. We show that
on the algebra of binary trees whose leaves are labeled by letters of an
alphabet containing at least three letters, a function is congruence preserving
if and only if it is polynomial.Comment: 9 pages, 1 figur
Random reals Ă la Chaitin with or without prefix-freeness
AbstractWe give a general theorem that provides examples of n-random reals Ă la Chaitin, for every nâ„1; these are halting probabilities of partial computable functions that are universal by adjunction for the class of all partial computable functions, The same result holds for the class functions of partial computable functions with prefix-free domain. Thus, the usual technical requirement of prefix-freeness on domains is an option which we show to be non-critical when dealing with universality by adjunction. We also prove that the condition of universality by adjunction (which, though particular, is a very natural case of optimality) is essential in our theorem
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