Enumeration of integral tetrahedra
- We determine the numbers of integral tetrahedra with diameter d up to isomorphism for all d<=1000 via computer enumeration. Therefore we give an algorithm that enumerates the integral tetrahedra with diameter at most d in O(d^5) time and an algorithm that can check the canonicity of a given integral tetrahedron with at most 6 integer comparisons. For the number of isomorphism classes of integral 4x4 matrices with diameter d fulfilling the triangle inequalities we derive an exact formula.
Measure and Integration on Lipschitz-Manifolds
Christian G. Simader
- The first part of this paper is concerned with various definitions of a k-dimensional Lipschitz-manifold and a discussion of the equivalence of these definitions. The second part is then devoted to the geometrically intrinsic construction of a sigma-algebra L of subsets of the manifold and a measure on L.