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pro vyhledávání: '"Pitsch, Wolfgang"'
We show that various methods for explicitly building resolutions of unbounded complexes in fact fail when applied to a rather simple and explicit complex. We show that one way to rescue these methods is to assume Roos (Ab.4$^*$)-$k$ axiom, which we a
Externí odkaz:
http://arxiv.org/abs/2407.09741
Autor:
Pitsch, Wolfgang, Riba, Ricard
We study the behaviour of the Casson invariant $\lambda$, its square, and Othsuki's second invariant $\lambda_2$ as functions on the Johnson subgroup of the mapping class group. We show that since $\lambda$ and $d_2 = \lambda_2 - 18 \lambda^2$ are in
Externí odkaz:
http://arxiv.org/abs/2311.09924
Autor:
Balacheff, Florent, Pitsch, Wolfgang
Consider a finite connected $2$-complex $X$ endowed with a piecewise Riemannian metric and whose fundamental group is freely indecomposable, of rank at least $3$, and in which every $2$-generated subgroup is free. In this paper we show that we can al
Externí odkaz:
http://arxiv.org/abs/2304.10924
Autor:
Pitsch, Wolfgang, Scherer, Jérôme
We prove that there is an action of the cyclic group $\mathbf{C}_2$ on the $10$-dimensional Floyd manifold which turns it into a conjugation manifold. The submanifold of fixed points is the $5$-dimensional Floyd manifold, whose cohomology is isomorph
Externí odkaz:
http://arxiv.org/abs/2105.04868
Autor:
Pitsch, Wolfgang
It is a classical fact that Wall's index of a triplet of Lagrangians in a symplectic space over a field $k$ defines a $2$-cocycle $\mu_W$ on the associated symplectic group with values in the Witt group of $k$. Moreover, modulo the square of the fund
Externí odkaz:
http://arxiv.org/abs/2105.04337
Autor:
Riba, Ricard, Pitsch, Wolfgang
We study the relation between the set of oriented $\mathbb{Z}/d$-homology $3$-spheres and the level-$d$ mapping class groups, the kernels of the canonical maps from the mapping class group of an oriented surface to the symplectic group with coefficie
Externí odkaz:
http://arxiv.org/abs/2103.15519
Autor:
Funar, Louis, Pitsch, Wolfgang
Publikováno v:
North-Western European J. Math. 8 (2022), 111-166
We give alternative computations of the Schur multiplier of $Sp(2g,\mathbb Z/D\mathbb Z)$, when $D$ is divisible by 4 and $g\geq 4$: a first one using $K$-theory arguments based on the work of Barge and Lannes and a second one based on the Weil repre
Externí odkaz:
http://arxiv.org/abs/2004.04129
Autor:
Pitsch, Wolfgang, Scherer, Jérôme
Publikováno v:
Proceedings of the Royal Society of Edinburgh: Section A Mathematics 151 (2021) 509-524
Conjugation spaces are topological spaces equipped with an involution such that their fixed points have the same mod $2$ cohomology (as a graded vector space, a ring, and even an unstable algebra) but with all degrees divided by two, generalizing the
Externí odkaz:
http://arxiv.org/abs/1911.13140
Conjugation spaces are equipped with an involution such that the fixed points have the same mod 2 cohomology (as a graded vector space, a ring, and even an unstable algebra) but with all degrees divided by 2, generalizing the classical examples of co
Externí odkaz:
http://arxiv.org/abs/1908.03088