in this paper, we study a class of finsler metrics which contains the class of p-reducible andgeneral relatively isotropic landsberg metrics, as special cases. we prove that on a compact finsler manifold,this class of metrics is nothing other than randers metrics. finally, we study this class of finsler metrics withscalar flag curvature and find a condition under which these metrics reduce to r...

A double 2-(v,k,2λ) design is a design which is reducible into two 2-(v,k,λ) designs. It is called uniquely reducible if it has, up to equivalence, only one reduction. We present properties of uniquely reducible double designs which show that their total number can be determined if only the designs with non-trivial automorphisms are classified with respect to their automorphism group. As an app...

A program is rst-order reducible (FO-reducible) with respect to (wrt) a set of integrity constraints if there exists a rst-order theory T such that the set of models for T is exactly the set of intended models for the program wrt all possible EDB's. In this case, we say that P is FO-reducible to T wrt IC. For FO-reducible programs, it is possible to characterize, using rst-order logic implicati...

Recently Glaÿer et al. have shown that for many classes C including PSPACE and NP it holds that all of its nontrivial many-one complete languages are autoreducible. This immediately raises the question of whether all many-one complete languages are Turing self-reducible for such classes C. This paper considers a simpler version of this question whether all PSPACE-complete (NPcomplete) languages...