dc.description |
Let be a space with probability measure μ
for which the notion of symmetry is defined. Given A µ , let
ms(A) denote the supremum of μ(B) over symmetric B µ A. An
r-coloring of is a measurable map  : ! {1, . . . , r} possi-
bly undefined on a set of measure 0. Given an r-coloring Â, let
ms(; Â) = max1·i·r ms(Â−1(i)). With each space we associate
a Ramsey type number ms(, r) = infÂms(; Â). We call a col-
oring  congruent if the monochromatic classes Â−1(1), . . . , Â−1(r)
are pairwise congruent, i.e., can be mapped onto each other by a
symmetry of . We define ms?(, r) to be the infimum of ms(; Â)
over congruent Â.
We prove that ms(S1, r) = ms?(S1, r) for the unitary circle S1
endowed with standard symmetries of a plane, estimate ms?([0, 1), r)
for the unitary interval of reals considered with central symmetry,
and explore some other regularity properties of extremal colorings
for various spaces. |
uk_UA |