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Algebraic filling inequalities and cohomological width. (English) Zbl 1459.57032

For a continuous map \(f:X\to Y\) between topological spaces the cohomological width of \(f\), width\(_*(f;R)\), is the maximal rank of the restriction homomorphisms \(H^*(X;R)\to H^*(f^{-1}(y);R)\), over all \(y\in Y\), in Čech cohomology with coefficients in a ring \(R\). The minimum of width\(_*(f;R)\) over all continuous maps \(f:X\to Y\) is the cohomological width of \(X\) over \(Y\), denoted by width\(_*(X/Y;R)\). In [Geom. Funct. Anal. 19, No. 3, 743–841 (2009; Zbl 1195.58010); ibid. 20, No. 2, 416–526 (2010; Zbl 1251.05039)] M. Gromov obtained lower bounds for the cohomological width in the case that \(X=T^n\) is a torus and \(Y\) a finite-dimensional simplicial complex. The present paper improves and generalizes the results of Gromov. In addition to \(X\) being a torus the author considers products \((S^p)^n\) of spheres. The first main theorem states that width\(_1(T^n/N;R)=n-\dim N\) where \(N\) is a manifold. This result is optimal as the projections \(T^n\to T^q\) show. The second main theorem states that width\(_p((S^p)^n/N);\mathbb{Q})\ge n-\dim N\), provided \(p\ge3\) is odd and \(n\le p-2\).

MSC:

57R35 Differentiable mappings in differential topology
58K15 Topological properties of mappings on manifolds
55N05 Čech types
55P62 Rational homotopy theory
55S35 Obstruction theory in algebraic topology

References:

[1] 10.1016/0040-9383(62)90016-2 · Zbl 0118.18503 · doi:10.1016/0040-9383(62)90016-2
[2] 10.1112/jtopol/jtq014 · Zbl 1196.53028 · doi:10.1112/jtopol/jtq014
[3] 10.1007/978-1-4613-0105-9 · doi:10.1007/978-1-4613-0105-9
[4] ; Félix, Algebraic models in geometry. Oxford Graduate Texts in Mathematics, 17 (2008) · Zbl 1149.53002
[5] 10.4310/jdg/1214509283 · Zbl 0515.53037 · doi:10.4310/jdg/1214509283
[6] 10.1007/s00039-009-0021-7 · Zbl 1195.58010 · doi:10.1007/s00039-009-0021-7
[7] 10.1007/s00039-010-0073-8 · Zbl 1251.05039 · doi:10.1007/s00039-010-0073-8
[8] 10.1007/978-3-642-39449-2_11 · Zbl 1317.01017 · doi:10.1007/978-3-642-39449-2_11
[9] 10.1007/978-1-4684-9449-5 · Zbl 0356.57001 · doi:10.1007/978-1-4684-9449-5
[10] 10.1007/978-0-387-21752-9 · doi:10.1007/978-0-387-21752-9
[11] 10.7146/math.scand.a-11931 · Zbl 0442.57011 · doi:10.7146/math.scand.a-11931
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