منابع مشابه
On Two Families of Multiset Tree Automata
The relation between the membrane structures of P systems and an extension of tree automata which introduces multisets in the transition function has been proposed in previous works. Here we propose two features of tree automata which have been previously studied (namely, reversibility and local testability) in order to extend them to multiset tree automata. The characterization of these famili...
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Let A be an integral k-algebra of finite type over a field k of characteristic zero. Let F be a family of k-derivations on A and MF the A-module spanned by F . In this paper, we generalise a result due to A. Nowicki and construct an element ∂ of MF such that ker ∂ = ∩d∈Fker d. Such a derivation is called F-minimal. Then we establish a density theorem for F-minimal derivations in MF .
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Background. Large scale metagenomic projects aim to extract biodiversity knowledge between different environmental conditions. Current methods for comparing microbial communities face important limitations. Those based on taxonomical or functional assignation rely on a small subset of the sequences that can be associated to known organisms. On the other hand, de novo methods, that compare the w...
متن کاملAn Upper Bound on the Sizes of Multiset-Union-Free Families
Let F1 and F2 be two families of subsets of an n-element set. We say that F1 and F2 are multiset-union-free if for any A,B ∈ F1 and C,D ∈ F2 the multisets A ⊎ C and B ⊎D are different, unless both A = B and C = D. We derive a new upper bound on the maximal sizes of multiset-union-free pairs, improving a result of Urbanke and Li.
متن کاملExtreme k-families
Let P be a poset. A subset A of P is a k-family ii A contains no (k+1)-element chain. For i 1, let A i be the set of elements of A at depth i?1 in A. The k-families of P can be ordered by deening A B ii for all i, A i is included in the order ideal generated by B i. This paper examines minimal r-element k-families, deened as k-families A such that A = r and for every B < A, B < r. Minimal k-fam...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1988
ISSN: 0012-365X
DOI: 10.1016/0012-365x(88)90013-1