In this paper we propose a method to automatically infer algebraic property-oriented specifications from Term Rewriting Systems. Namely, having three semantics with suitable properties, given the source code of a TRS we infer a specification which consists of a set of most general equations relating terms that rewrite, for all possible instantiations, to the same set of constructor terms. The s...

We investigate Tukey functions from the ideal of all closed nowhere dense subsets of 2N. In particular, we answer an old question of Isbell and Fremlin by showing that this ideal is not Tukey reducible to the ideal of density zero subsets of N. We also prove non-existence of various special types of Tukey reductions from the nowhere dense ideal to analytic P-ideals. In connection with these res...

We take a set Ω of n points and an arrangement Σ of m lines in the plane which avoid these points but separate any two of them. We suppose these satisfy the following unboundedness property: for each point x ∈ Ω there is a homotopy from Σ to Σ′ avoiding Ω so that x is in an unbounded component of the complement of Σ′. It is proved that then n ≤ 2m. This result is required to partially solve a p...

This paper describes a method to recover entire 3D shape of a building from an image sequence. This is a kind of "Shape and Motion recovery" problem, whereas conventional methods do not work well with images taken around a large object in near distance. Since such image sequence is a set of partial observations, 3D recovery becomes unstable. We first discuss the property of local minima of the ...

Billey, Jockusch, and Stanley characterized 321-avoiding permutations by a property of their reduced decompositions. This paper generalizes that result with a detailed study of permutations via their reduced decompositions and the notion of pattern containment. These techniques are used to prove a new characterization of vexillary permutations in terms of their principal dual order ideals in a ...