{ "id": "1506.06300", "version": "v1", "published": "2015-06-20T22:27:18.000Z", "updated": "2015-06-20T22:27:18.000Z", "title": "The co-rank of the fundamental group: the direct product, the first Betti number, and the topology of foliations", "authors": [ "Irina Gelbukh" ], "comment": "Accepted to Mathematica Slovaca, 2015", "categories": [ "math.AT" ], "abstract": "We study $b'_1(M)$, the co-rank of the fundamental group of a smooth closed connected manifold $M$. We calculate this value for the direct product of manifolds. We characterize the set of all possible combinations of $b'_1(M)$ and the first Betti number $b_1(M)$ by explicitly constructing manifolds with any possible combination of $b'_1(M)$ and $b_1(M)$ in any given dimension. Finally, we apply our results to the topology of Morse form foliations. In particular, we construct a manifold $M$ and a Morse form $\\omega$ on it for any possible combination of $b'_1(M)$, $b_1(M)$, $m(\\omega)$, and $c(\\omega)$, where $m(\\omega)$ is the number of minimal components and $c(\\omega)$ is the maximum number of homologically independent compact leaves of $\\omega$.", "revisions": [ { "version": "v1", "updated": "2015-06-20T22:27:18.000Z" } ], "analyses": { "subjects": [ "14F35", "57N65", "57R30" ], "keywords": [ "first betti number", "direct product", "fundamental group", "combination", "morse form foliations" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2015arXiv150606300G" } } }