144 research outputs found
The Matiyasevich Theorem. Preliminaries
In this article, we prove selected properties of Pell’s equation that are essential to finally prove the Diophantine property of two equations. These equations are explored in the proof of Matiyasevich’s negative solution of Hilbert’s tenth problem.This work has been financed by the resources of the Polish National Science Centre granted by decision no. DEC-2015/19/D/ST6/01473.Institute of Informatics University of Białystok, Białystok, PolandMarcin Acewicz and Karol Pak. Pell’s equation. Formalized Mathematics, 25(3):197-204, 2017. doi: 10.1515/forma-2017-0019.Zofia Adamowicz and Paweł Zbierski. Logic of Mathematics: A Modern Course of Classical Logic. Pure and Applied Mathematics: A Wiley Series of Texts, Monographs and Tracts. Wiley-Interscience, 1997.Martin Davis. Hilbert’s tenth problem is unsolvable. The American Mathematical Monthly, Mathematical Association of America, 80(3):233-269, 1973. doi: 10.2307/2318447.Yoshinori Fujisawa and Yasushi Fuwa. The Euler’s function. Formalized Mathematics, 6 (4):549-551, 1997.Xiquan Liang, Li Yan, and Junjie Zhao. Linear congruence relation and complete residue systems. Formalized Mathematics, 15(4):181-187, 2007. doi: 10.2478/v10037-007-0022-7.Robert Milewski. Natural numbers. Formalized Mathematics, 7(1):19-22, 1998.Rafał Ziobro. Fermat’s Little Theorem via divisibility of Newton’s binomial. Formalized Mathematics, 23(3):215-229, 2015. doi: 10.1515/forma-2015-0018.25431532
Compressed Subsequence Matching and Packed Tree Coloring
We present a new algorithm for subsequence matching in grammar compressed
strings. Given a grammar of size compressing a string of size and a
pattern string of size over an alphabet of size , our algorithm
uses space and or time. Here
is the word size and is the number of occurrences of the pattern. Our
algorithm uses less space than previous algorithms and is also faster for
occurrences. The algorithm uses a new data structure
that allows us to efficiently find the next occurrence of a given character
after a given position in a compressed string. This data structure in turn is
based on a new data structure for the tree color problem, where the node colors
are packed in bit strings.Comment: To appear at CPM '1
On the complexity of nonlinear mixed-integer optimization
This is a survey on the computational complexity of nonlinear mixed-integer
optimization. It highlights a selection of important topics, ranging from
incomputability results that arise from number theory and logic, to recently
obtained fully polynomial time approximation schemes in fixed dimension, and to
strongly polynomial-time algorithms for special cases.Comment: 26 pages, 5 figures; to appear in: Mixed-Integer Nonlinear
Optimization, IMA Volumes, Springer-Verla
(Un)Decidability Results for Word Equations with Length and Regular Expression Constraints
We prove several decidability and undecidability results for the
satisfiability and validity problems for languages that can express solutions
to word equations with length constraints. The atomic formulas over this
language are equality over string terms (word equations), linear inequality
over the length function (length constraints), and membership in regular sets.
These questions are important in logic, program analysis, and formal
verification. Variants of these questions have been studied for many decades by
mathematicians. More recently, practical satisfiability procedures (aka SMT
solvers) for these formulas have become increasingly important in the context
of security analysis for string-manipulating programs such as web applications.
We prove three main theorems. First, we give a new proof of undecidability
for the validity problem for the set of sentences written as a forall-exists
quantifier alternation applied to positive word equations. A corollary of this
undecidability result is that this set is undecidable even with sentences with
at most two occurrences of a string variable. Second, we consider Boolean
combinations of quantifier-free formulas constructed out of word equations and
length constraints. We show that if word equations can be converted to a solved
form, a form relevant in practice, then the satisfiability problem for Boolean
combinations of word equations and length constraints is decidable. Third, we
show that the satisfiability problem for quantifier-free formulas over word
equations in regular solved form, length constraints, and the membership
predicate over regular expressions is also decidable.Comment: Invited Paper at ADDCT Workshop 2013 (co-located with CADE 2013
FPTAS for optimizing polynomials over the mixed-integer points of polytopes in fixed dimension
We show the existence of a fully polynomial-time approximation scheme (FPTAS)
for the problem of maximizing a non-negative polynomial over mixed-integer sets
in convex polytopes, when the number of variables is fixed. Moreover, using a
weaker notion of approximation, we show the existence of a fully
polynomial-time approximation scheme for the problem of maximizing or
minimizing an arbitrary polynomial over mixed-integer sets in convex polytopes,
when the number of variables is fixed.Comment: 16 pages, 4 figures; to appear in Mathematical Programmin
Decidability of Univariate Real Algebra with Predicates for Rational and Integer Powers
We prove decidability of univariate real algebra extended with predicates for
rational and integer powers, i.e., and . Our decision procedure combines computation over real algebraic
cells with the rational root theorem and witness construction via algebraic
number density arguments.Comment: To appear in CADE-25: 25th International Conference on Automated
Deduction, 2015. Proceedings to be published by Springer-Verla
On the l.c.m. of shifted Fibonacci numbers
Let be the sequence of Fibonacci numbers. Guy and
Matiyasevich proved that \begin{equation*} \log \operatorname{lcm} (F_1, F_2,
\dots, F_n) \sim \frac{3 \log \alpha}{\pi^2} \cdot n^2 \quad \text{as } n \to
+\infty, \end{equation*} where is the least common
multiple and is the golden ratio.
We prove that for every periodic sequence in
there exists an effectively computable rational number
such that \begin{equation*} \log \operatorname{lcm} (F_3 +
s_3, F_4 + s_4, \dots, F_n + s_n) \sim \frac{3 \log \alpha}{\pi^2} \cdot
C_\mathbf{s} \cdot n^2 , \quad \text{as } n \to +\infty . \end{equation*}
Moreover, we show that if is a sequence of independent
uniformly distributed random variables in then \begin{equation*}
\mathbb{E}\big[\log \operatorname{lcm} (F_3 + s_3, F_4 + s_4, \dots, F_n +
s_n)\big] \sim \frac{3 \log \alpha}{\pi^2} \cdot \frac{15 \operatorname{Li}_2(1
/ 16)}{2} \cdot n^2 , \quad \text{as } n \to +\infty , \end{equation*} where
is the dilogarithm function
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