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- Martin Grüttmüller, Sven Hartmann, Thomas Kalinowski, Uwe Leck, Ian T. Roberts
- Electr. J. Comb.
- 2009

We study maximal families A of subsets of [n] = {1, 2,. .. , n} such that A contains only pairs and triples and A ⊆ B for all {A, B} ⊆ A, i.e. A is an antichain. For any n, all such families A of minimum size are determined. This is equivalent to finding all graphs G = (V, E) with |V | = n and with the property that every edge is contained in some triangle… (More)

- Sven Hartmann, Uwe Leck, Sebastian Link
- Comput. J.
- 2011

Keys allow a database management system to uniquely identify tuples in a database. Consequently, the class of keys is of great significance for almost all data processing tasks. In the relational model of data, keys have received considerable interest and are well understood. However, for efficient means of data processing most commercial relational… (More)

- Hans-Dietrich O. F. Gronau, Martin Grüttmüller, Sven Hartmann, Uwe Leck, Volker Leck
- Des. Codes Cryptography
- 2002

- Henning Köhler, Uwe Leck, Sebastian Link, Henri Prade
- JELIA
- 2014

Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Abstract. Possibility theory is applied to introduce and reason about the fundamental notion of a key for uncertain data. Uncertainty is modeled… (More)

- Uwe Leck
- Graphs and Combinatorics
- 2002

- Uwe Leck
- Discrete Mathematics
- 2001

We consider the poset of all submatrices of a given matrix, ordered by containment. The unique rank function for this poset is given by r(M) = R(M)+C(M)?1, where R(M) and C(M) denote the number of rows and columns of a nonempty matrix M, respectively, and the rank of the empty matrix is 0. For xed k and i our objective is to nd a set M of submatrices M 1 ;… (More)

- Sergei L. Bezrukov, Uwe Leck
- SIAM J. Discrete Math.
- 2009

- Uwe Leck, Ian T. Roberts, Jamie Simpson
- Australasian J. Combinatorics
- 2012

It is proved that, for any positive integer m, the weight of the union-closure of any m distinct 2-sets is at least as large as the weight of the union-closure of the first m 2-sets in squashed (antilexicographic) order, where all i-sets have the same non-negative weight w i with w i ≤ w i+1 for all i, and the weight of a family of sets is the sum of the… (More)

- Uwe Leck, Volker Leck
- Discrete Applied Mathematics
- 1999

An Orthogonal Double Cover (ODC) of the complete graph K n by an almost-hamiltonian cycle is a decomposition of 2K n into cycles of length nÀ1 such that the intersection of any two of them is exactly one edge. We introduce a new class of such decompositions. If n is a prime, the special structure of such a decomposition allows to expand it to an ODC of K… (More)