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The 9th Logic and Computation Seminar

Hold Date 2011-11-26 13:00~2011-11-26 18:00

Place Lecture Room L-3, Faculty of Mathematics building, Ito Campus

Object person  

Speaker Reynald Affeldt (AIST), Akihiro MUNEMASA (Tohoku University), Yohji AKAMA (Tohoku University), Noriko WAKABAYASHI (Kyushu Sangyo University), Naoyuki SHINOHARA (Network Security Research Institute, NICT)

supported by
"Education and Research Hub for Mathematics-for-Industry" (Program Leader:Masato WAKAYAMA)

13:00- Reynald Affeldt (AIST)
        Instrumenting Error-correcting Codes with SSReflect
Our motivation is to provide in the Coq proof-assistant formal
definitions and lemmas about error-correcting codes. The resulting
toolkit could enable, for example, formal verification of
implementations of cryptographic schemes based on error-correcting
codes. For that purpose, we use the SSReflect library, that provides
an integrated formalization of matrices and polynomials. As a
technical introduction to formal verification in the Coq
proof-assistant, we report on the formalization of basic
properties of error-correcting codes and probabilities.

14:00- Akihiro MUNEMASA (Tohoku University)
        Super Catalan numbers and Krawtchouk polynomials
In 1992, Ira Gessel defined super Catalan number \(S(m,n)\) as
S(m,n) = \frac{(2m)!(2n)!}{m!n!(m+n)!},
where \(m,n\) are positive integers, and showed
that \(S(m,n)\) is an integer.
In this talk, we point out an interpretation of
\(S(m,n)\) as a special value of a
Krawtchouk polynomial \(K_j^d(x)\).
Krawtchouk polynomials appear as the coefficients of the so-called
MacWilliams identities, and
also as the eigenvalues of the distance-\(j\) graph of the \(d\)-dimensional
cube. Our interpretation shows that
\(\{(-1)^mS(m,n)\mid m,n\geq0,\;m+n=j\}\) coincides with
the set of non-zero eigenvalues of the distance-\(j\) graph of the
\(2j\)-dimensional cube.
This is joint work with Evangelos Georgiadis and Hajime Tanaka.

15:00- Yohji AKAMA (Tohoku University)
        Set systems: Order types, continuous nondeterministic deformations, and quasi-orders
By reformulating a learning process of a set system L as a game between
Teacher and Learner, we define the order type of L to be the order type of
the game tree, if the tree is well-founded. The features of the order type
of L (dim L in symbol) are (1) we can represent any well-quasi-order (wqo
for short) by the set system L of the upper-closed sets of the wqo such that
the maximal order type of the wqo is equal to dim L; (2) dim L is an upper
bound of the mind-change complexity of L. dim L is defined iff L has a
finite elasticity (fe for short), where, according to computational learning
theory, if an indexed family of recursive languages has fe then it is
learnable by an algorithm from positive data. Regarding set systems as
subspaces of Cantor spaces, we prove that fe of set systems is preserved by
any continuous function which is monotone with respect to the set-inclusion.
By it, we prove that finite elasticity is preserved by various
(nondeterministic) language operators (Kleene-closure, shuffle-closure,
union, product, intersection, …). The monotone continuous functions
represent nondeterministic computations. If a monotone continuous function
has a computation tree with each node followed by at most n immediate
successors and the order type of a set system L is α, then the direct image
of L is a set system of order type at most n-adic diagonal Ramsey number of
α. Furthermore, we provide an order-type-preserving contravariant embedding
from the category of quasi-orders and finitely branching simulations between
them, into the complete category of subspaces of Cantor spaces and monotone
continuous functions having Girard’s linearity between them.(To appear in
Theoretical Computer Science doi:10.1016/j.tcs.2011.08.010 )

16:00- Noriko WAKABAYASHI (Kyushu Sangyo University)
        Double shuffle and Hoffman's relations for multiple L-star values

17:00- Naoyuki SHINOHARA (Network Security Research Institute, NICT)
        Primality proving and Grantham's problem
There are two kinds of algorithms to determine the primality of a given
integer. The one is a primality test which is efficient but probabilistic,
namely, it rarely makes a wrong answer. Another is a primality proving
that always gives a correct answer, but it is not so efficient.
In this talk, we consider to construct an efficient primality proving
by improving Quadratic Frobenius primality test. In order to achieve our
aim, we discuss Grantham's Problem.