6533b7dafe1ef96bd126e3a4

RESEARCH PRODUCT

Finitary shadows of compact subgroups of $$S(\omega )$$

B. Majcher-iwanow

subject

Algebra and Number TheoryCompact groups of permutationsDistribution (number theory)Group (mathematics)010102 general mathematicsLattice (group)Almost containednessNatural number0102 computer and information sciences01 natural sciencesOmegaMeasure (mathematics)CombinatoricsOrthogonality010201 computation theory & mathematicsOrthogonality of finitary subgroupsFinitary0101 mathematicsMartin’s axiom.Mathematics

description

AbstractLet LF be the lattice of all subgroups of the group $$SF(\omega )$$SF(ω) of all finitary permutations of the set of natural numbers. We consider subgroups of $$SF(\omega )$$SF(ω) of the form $$C\cap SF(\omega )$$C∩SF(ω), where C is a compact subgroup of the group of all permutations. In particular, we study their distribution among elements of LF. We measure this using natural relations of orthogonality and almost containedness. We also study complexity of the corresponding families of compact subgroups of $$S(\omega )$$S(ω).

https://doi.org/10.1007/s00012-020-00658-6