منابع مشابه
Linking Numbers in Rational Homology 3-spheres, Cyclic Branched Covers and Infinite Cyclic Covers
We study the linking numbers in a rational homology 3-sphere and in the infinite cyclic cover of the complement of a knot. They take values in Q and inQ(Z[t, t−1]) respectively, where Q(Z[t, t−1]) denotes the quotient field of Z[t, t−1]. It is known that the modulo-Z linking number in the rational homology 3-sphere is determined by the linking matrix of the framed link and that the modulo-Z[t, ...
متن کاملRank Gradient of Cyclic Covers
If M is an orientable hyperbolic 3-manifold with finite volume and φ : π1(M) Z, the family of covers corresponding to {φ−1(nZ) |n ∈ N} has rank gradient 0 if and only if the Poincaré–Lefschetz dual of the class in H1(M ; Z) corresponding to φ is represented by a fiber. This generalizes a theorem of M. Lackenby. If M is closed, we give an explicit lower bound on the rank gradient. The proof uses...
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then V is a primitive Fano variety of dimensionM , that is, Pic V = ZKV and (−KV ) is ample. The purpose of this note is to sketch a proof of the following Theorem 1. A general (in the sense of Zariski topology) variety V is birationally superrigid. In particular, V admits no non-trivial structures of a rationally connected fibration, any birational map V 99K V ♯ onto a Fano variety with Q-fact...
متن کاملBranched Cyclic Covers and Finite Type Invariants
This work identifies a class of moves on knots which translate to m-equivalences of the associated p-fold branched cyclic covers, for a fixed m and any p (with respect to the Goussarov-Habiro filtration). These moves are applied to give a flexible (if specialised) construction of knots for which the Casson-Walker-Lescop invariant (for example) of their p-fold branched cyclic covers may be readi...
متن کاملOn Cyclic Covers and Perfect Models
The relationship between cyclic covers and perfect models of indefinite stratified deductive databases is discussed with respect to query answering, view updates and partial evaluation. The notion of a conjunctive answer to a database query is introduced, and such answers are shown to have a number of advantages over (the more commonly studied) “disjunctive” answers. The problem of computing co...
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ژورنال
عنوان ژورنال: Research in Number Theory
سال: 2019
ISSN: 2522-0160,2363-9555
DOI: 10.1007/s40993-019-0170-1