ar X iv : 0 90 5 . 14 04 v 1 [ m at h . D G ] 9 M ay 2 00 9 Time - like Salkowski and anti - Salkowski curves in Minkowski space

Spacelike Salkowski and anti-Salkowski Curves With a Spacelike Principal Normal in Minkowski 3-Space

A century ago, Salkowski [9] introduced a family of curves with constant curvature but non-constant torsion (Salkowski curves) and a family of curves with constant torsion but nonconstant curvature (anti-Salkowski curves). In this paper, we adapt definition of such curves to spacelike curves in Minkowski 3-space. Thereafter, we introduce an explicit parametrization of a spacelike Salkowski curv...

ar X iv : 0 90 5 . 45 11 v 1 [ m at h . A G ] 2 8 M ay 2 00 9 BLOWUPS IN TAME MONOMIAL IDEALS

We study blowups of affine n-space with center an arbitrary monomial ideal and call monomial ideals that render smooth blowups tame ideals. We give a combinatorial criterion to decide whether the blowup is smooth and apply this criterion to discuss a smoothing procedure proposed by Rosenberg, monomial building sets and permutohedra.

ar X iv : h ep - p h / 04 05 03 9 v 1 5 M ay 2 00 4 η , η ′ → π + π − γ with coupled channels

ar X iv : 0 90 5 . 04 56 v 1 [ m at h . L O ] 4 M ay 2 00 9 Non deterministic classical logic : the λ μ + + - calculus

In this paper, we present an extension of λμ-calculus called λμcalculus which has the following properties: subject reduction, strong normalization, unicity of the representation of data and thus confluence only on data types. This calculus allows also to program the parallel-or.

ar X iv : m at h - ph / 9 80 50 04 v 1 5 M ay 1 99 8 Five - Dimensional Tangent Vectors in Space - Time