منابع مشابه
Totally Free Expansions of Matroids
The aim of this paper is to give insight into the behaviour of inequivalent representations of 3-connected matroids. An element x of a matroid M is fixed if there is no extension MŒ of M by an element xŒ such that {x, xŒ} is independent and MŒ is unaltered by swapping the labels on x and xŒ. When x is fixed, a representation of M0x extends in at most one way to a representation of M. A 3-connec...
متن کاملOn Totally Free Expansions of Matroids
The aim of this paper is to give insight into the behaviour of inequivalent representations of 3{connected matroids. An element x of a matroid M is xed if there is no extension M 0 of M by an element x 0 such that fx;x 0 g is independent and M 0 is unaltered by swapping the labels on x and x 0. When x is xed, a representation of M nx extends in at most one way to a representation of M. A 3{conn...
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We introduce a noncommutative binary operation on matroids, called free product. We show that this operation respects matroid duality, and has the property that, given only the cardinalities, an ordered pair of matroids may be recovered, up to isomorphism, from its free product. We use these results to give a short proof of Welsh’s 1969 conjecture, which provides a progressive lower bound for t...
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Motivated by new ideas about the Higgs mass naturalness problem, we present realistic TeV-scale extensions of the Standard Model, into the gauge group SU(3)L ⊗ SU(3)R ⊗ SU(3)c, such that all gauge, Yukawa and quartic couplings can be extrapolated up to infinite energy. Three generations of chiral fermions and Higgses are needed, as well as some extra fermion.
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In this paper, I show that general recursive definitions can be represented in the free monad which supports the ‘effect’ of making a recursive call, without saying how these calls should be executed. Diverse semantics can be given within a total framework by suitable monad morphisms. The Bove-Capretta construction of the domain of a general recursive function can be presented datatype-generica...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series B
سال: 2002
ISSN: 0095-8956
DOI: 10.1006/jctb.2001.2068