منابع مشابه
Even Sets of Nodes on Sextic Surfaces
We determine the possible even sets of nodes on sextic surfaces in P, showing in particular that their cardinalities are exactly the numbers in the set {24, 32, 40, 56}. We also show that all the possible cases admit an explicit description. The methods that we use are an interplay of coding theory and projective geometry on one hand, of homological and computer algebra on the other. We give a ...
متن کاملEven Sets of Lines on Quartic Surfaces
5 Classification 10 5.1 Two lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.2 Four lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.3 Six lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4 Eight lines . . . . . . . . . . . . . . . . . . . . . . . . ....
متن کاملEven Sets of Nodes Are Bundle Symmetric
Let k be an algebraically closed field of characteristic p 6= 2 and let F := {f = 0} ⊆ Pk be a normal surface of degree d. Let π: F̃ → F be a minimal resolution of singularities. We denote by H ⊆ F a general plane section of F defined by a general linear form h. Assume, for simplicity, that F is a nodal surface (i.e. its singularities are only ordinary quadratic, nodes for short). Let ∆ be a sub...
متن کاملOn Even and Harmonic-Even Partial Cubes
Fukuda and Handa [7] asked whether every even partial cube G is harmonic-even. It is shown that the answer is positive if the isometric dimension of G equals its diameter which is in turn true for partial cubes with isometric dimension at most 6. Under an additional technical condition it is proved that an even partial cube G is harmonic-even or has two adjacent vertices whose diametrical verti...
متن کاملFinite groups have even more centralizers
For a finite group $G$, let $Cent(G)$ denote the set of centralizers of single elements of $G$. In this note we prove that if $|G|leq frac{3}{2}|Cent(G)|$ and $G$ is 2-nilpotent, then $Gcong S_3, D_{10}$ or $S_3times S_3$. This result gives a partial and positive answer to a conjecture raised by A. R. Ashrafi [On finite groups with a given number of centralizers, Algebra Collo...
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ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 2015
ISSN: 0166-218X
DOI: 10.1016/j.dam.2014.08.038