On the number of databases and closure operations
Theoretical Computer Science
Functional dependencies in relational databases: a lattice point of view
Discrete Applied Mathematics - Special issue on combinatorial problems in databases
Discrete Mathematics
Isomorph-free exhaustive generation
Journal of Algorithms
Latticial structures in data analysis
Theoretical Computer Science
Formal Concept Analysis: Mathematical Foundations
Formal Concept Analysis: Mathematical Foundations
Discrete Applied Mathematics - Special issue: The 1998 conference on ordinal and symbolic data analysis (OSDA '98)
Recursive decomposition and bounds of the lattice of Moore co-families
Annals of Mathematics and Artificial Intelligence
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Given a set Un={0,1,...,n−1}, a collection $\mathcal{M}$ of subsets of Un that is closed under intersection and contains Un is known as a Moore family. The set of Moore families for a given n, denoted by Mn, increases very quickly with n, thus |M3| is 61 and |M4| is 2480. In [1] the authors determined the number for n=6 and stated a 24h- computation-time. Thus, the number for n=7 can be considered as an extremely difficult technical challenge. In this paper, we introduce a counting strategy for determining the number of Moore families for n=7 and we give the exact value : 14 087 648 235 707 352 472. Our calculation is particularly based on the enumeration of Moore families up to an isomorphism for n ranging from 1 to 6.