منابع مشابه
Overlapping Pfaffians
A combinatorial construction proves an identity for the product of the Pfaffian of a skew-symmetric matrix by the Pfaffian of one of its submatrices. Several applications of this identity are followed by a brief history of Pfaffians. 0. Definitions. Let X be a possibly infinite index set. We consider quantities f [xy] defined on ordered pairs of elements of X , satisfying the law of skew symmet...
متن کاملGraphical Condensation, Overlapping Pfaffians and Superpositions of Matchings
The purpose of this note is to exhibit clearly how the “graphical condensation” identities of Kuo, Yan, Yeh and Zhang follow from classical Pfaffian identities by the Kasteleyn–Percus method for the enumeration of matchings. Knuth termed the relevant identities “overlapping Pfaffian” identities and the key concept of proof “superpositions of matchings”. In our uniform presentation of the materi...
متن کاملJu n 20 09 GRAPHICAL CONDENSATION , OVERLAPPING PFAFFIANS AND SUPERPOSITIONS OF MATCHINGS MARKUS
The purpose of this note is to exhibit clearly how the “graphical condensation” identities of Kuo, Yan, Yeh and Zhang follow from classical Pfaffian identities by the Kasteleyn–Percus method for the enumeration of matchings. Knuth termed the relevant identities “overlapping Pfaffian” identities and the key concept of proof “superpositions of matchings”. In our uniform presentation of the materi...
متن کاملFour-by-four Pfaffians
This paper shows that the general hypersurface of degree ≥ 6 in projective four space cannot support an indecomposable rank two vector bundle which is Arithmetically CohenMacaulay and four generated. Equivalently, the equation of the hypersurface is not the Pfaffian of a four by four minimal skewsymmetric matrix.
متن کاملReplacing Pfaffians and applications
We present some Pfaffian identities, which are completely different from the Plücker relations. As consequences we obtain a quadratic identity for the number of perfect matchings of plane graphs, which has a simpler form than the formula by Yan et al (Graphical condensation of plane graphs: a combinatorial approach, Theoret. Comput. Sci., to appear), and we also obtain some new determinant iden...
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ژورنال
عنوان ژورنال: The Electronic Journal of Combinatorics
سال: 1995
ISSN: 1077-8926
DOI: 10.37236/1263