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The relative coincidence Nielsen number

Jerzy Jezierski (1996)

Fundamenta Mathematicae

We define a relative coincidence Nielsen number N r e l ( f , g ) for pairs of maps between manifolds, prove a Wecken type theorem for this invariant and give some formulae expressing N r e l ( f , g ) by the ordinary Nielsen numbers.

The Spaces of Closed Convex Sets in Euclidean Spaces with the Fell Topology

Katsuro Sakai, Zhongqiang Yang (2007)

Bulletin of the Polish Academy of Sciences. Mathematics

Let C o n v F ( ) be the space of all non-empty closed convex sets in Euclidean space ℝ ⁿ endowed with the Fell topology. We prove that C o n v F ( ) × Q for every n > 1 whereas C o n v F ( ) × .

The topology of the Banach–Mazur compactum

Sergey Antonyan (2000)

Fundamenta Mathematicae

Let J(n) be the hyperspace of all centrally symmetric compact convex bodies A n , n ≥ 2, for which the ordinary Euclidean unit ball is the ellipsoid of maximal volume contained in A (the John ellipsoid). Let J 0 ( n ) be the complement of the unique O(n)-fixed point in J(n). We prove that: (1) the Banach-Mazur compactum BM(n) is homeomorphic to the orbit space J(n)/O(n) of the natural action of the orthogonal group O(n) on J(n); (2) J(n) is an O(n)-AR; (3) J 0 ( 2 ) / S O ( 2 ) is an Eilenberg-MacLane space 𝐊 ( , 2 ) ; (4) B M 0 ( 2 ) = J 0 ( 2 ) / O ( 2 ) is noncontractible;...

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