17,406 research outputs found
Young classes of permutations
We characterise those classes of permutations having the property that for
every tableau shape either every permutation of that shape or no permutation of
that shape belongs to the class. The characterisation is in terms of the
dominance order for partitions (and their conjugates) and shows that for any
such class there is a constant k such that no permutation in the class can
contain both an increasing and a decreasing sequence of length k.Comment: 11 pages, this is the final version as accepted by the Australasian
Journal of Combinatorics. Some more minor typos have been correcte
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2×2 monotone grid classes are finitely based
In this note, we prove that all 2×2 monotone grid classes are finitely based, i.e., defined by a finite collection of minimal forbidden permutations. This follows from a slightly more general result about certain 2×2 (generalized) grid classes having two monotone cells in the same row
1st Report of the Working Group on Standard Development
The initial meeting of the working group on standard development took place at the 1st SAFO-Workshop, September 2003, in Florence. In accordance with the main topic of the Workshop, the discussion was primarily focused on the relationship between socio-economic aspects of the standards and the issue of animal health and food safety in organic farming.
The report cover the additional issues discussed in the 1st Working Group meeting in Florence
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