Английская Википедия:Capped grope
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In mathematics, a grope is a construction used in 4-dimensional topology, introduced by Шаблон:Harvtxt and named by Шаблон:Harvtxt "because of its multitudinous fingers". Capped gropes were used by Шаблон:Harvtxt as a substitute for Casson handles, thatШаблон:Vague work better for non-simply-connected 4-manifolds.
A capped surface in a 4-manifold is roughly a surface together with some 2-disks, called caps, whose boundaries generate the fundamental group of the surface. A capped grope is obtained by repeatedly replacing the caps of a capped surface by another capped surface. Capped surfaces and capped gropes are studied in Шаблон:Harvtxt.
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