منابع مشابه
Monodromy Groups of Hurwitz-type Problems
We solve the Hurwitz monodromy problem for degree 4 covers. That is, the Hurwitz space H4,g of all simply branched covers of P of degree 4 and genus g is an unramified cover of the space P2g+6 of (2g + 6)-tuples of distinct points in P. We determine the monodromy of π1(P2g+6) on the points of the fiber. This turns out to be the same problem as the action of π1(P2g+6) on a certain local system o...
متن کاملHurwitz groups as monodromy groups of dessins: several examples
We present a number of examples to illustrate the use of small quotient dessins as substitutes for their often much larger and more complicated Galois (minimal regular) covers. In doing so we employ several useful group-theoretic techniques, such as the Frobenius character formula for counting triples in a finite group, pointing out some common traps and misconceptions associated with them. Alt...
متن کاملThe Hurwitz Action and Braid Group Orderings
In connection with the so-called Hurwitz action of homeomorphisms in ramified covers we define a groupoid, which we call a ramification groupoid of the 2sphere, constructed as a certain path groupoid of the universal ramified cover of the 2-sphere with finitely many marked-points. Our approach to ramified covers is based on cosheaf spaces, which are closely related to Fox’s complete spreads. A ...
متن کاملThe monodromy group of a truncated simplex
In this paper we investigate the monodromy groups of the truncated simplices of all possible ranks and investigate related structures. In particular, we demonstrate that the monodromy group of a truncated simplex is the direct product of symmetric groups.
متن کاملHurwitz monodromy, spin separation and higher levels of a Modular Tower
Each finite p-perfect group G (p a prime) has a universal central p-extension coming from the p part of its Schur multiplier. Serre gave a StiefelWhitney class approach to analyzing spin covers of alternating groups (p = 2) aimed at geometric covering space problems that included their regular realization for the Inverse Galois Problem. A special case of a general result is that any finite simp...
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ژورنال
عنوان ژورنال: Journal of Algebra
سال: 1974
ISSN: 0021-8693
DOI: 10.1016/0021-8693(74)90155-0