slideshow 3

Set Theory & Analysis

Spectre of a set

Piotr Nowakowski
University of Lodz, Poland


Thursday, 9. March 2023 - 10:00 to 11:30
Let (X,+) be an Abelian group. Let A be a subset of X. We define the spectre of a set A as
S(A) := {x in X: for all y in A we have y+x in A or y-x in A}.
We will show some properties of the spectre of a set and its connections with centre of distance and achievement sets 
of absolutely convergent series.

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