This paper addresses the crucial issue in the design of a proof development system of how to deal with partial functions and the related question of how to treat undefined terms. Often the problem is avoided by artificially making all functions total. However, that does not correspond to the practice of everyday mathematics. In type theory partial functions are modeled by giving functions extra...

– We prove the existence of low energy excitations in insulating systems at general filling factor under certain conditions, and discuss in which cases these may be identified as topological excitations. In the specific case of half-filling this proof provides a significantly shortened proof of the recent higher dimensional Lieb-Schultz-Mattis theorem. The classic 1961 result of Lieb, Schultz, ...

Starting from second-order conditions for C scalar unconstrained optimization problems described in terms of the second-order Dini directional derivative, we pose the problem, whether similar conditions for C vector optimization problems can be derived. We define second-order Dini directional derivatives for vector functions and apply them to formulate such conditions as a Conjecture. The proof...

In this paper we present a method for determining some variations of a singular trajectory of an affine control system. These variations provide necessary optimality conditions which may distinguish between maximizing and minimizing problems. The generalized Legendre-Clebsch conditions are an example of these type of conditions.

and Applied Analysis 3 Theorem 1.3 see 12 . Let c2k c2k 1 μ k/k!, μ ∈ 0, 1 . For any positive integer n and 0 < θ < π , then i ∑n k 0 ck cos kθ > 0 if and only if 0 < μ ≤ μ0, ii ∑2n 1 k 1 ck sin kθ > 0 if and only if 0 < μ ≤ μ0, iii ∑2n k 1 ck sin kθ > 0 if 0 < μ ≤ 1/2. Here μ0 0.691556 · · · is the unique root in 0, 1 of ∫3π/2 0 cos t t1−μ dt 0. 1.6 2. Main Results For our purpose, it will be ...

This paper deals with optimal control problems for systems affine in the control variable. We have nonnegativity constraints on the control, and finitely many equality and inequality constraints on the final state. First, we obtain second order necessary optimality conditions. Secondly, we get a second order sufficient condition for the scalar control case. The results use in an essential way t...

We study an extension of first-order logic that allows to express cardinality conditions in a similar way as SQL’s COUNT operator. The corresponding logic FOC(P) was introduced by Kuske and Schweikardt [16], who showed that query evaluation for this logic is fixedparameter tractable on classes of databases of bounded degree. In the present paper, we first show that the fixed-parameter tractabil...