TY - JOUR
T1 - The failure of the uncountable non-commutative Specker Phenomenon
AU - Shelah, Saharon
AU - Strüngmann, Lutz
PY - 2001
Y1 - 2001
N2 - Higman proved in 1952 that every free group is non-commutatively slender, that is, for a free group G and for a homomorphism h from the free complete product xωℤ of countably many copies of ℤ into G, there exists a finite subset F ⊆ ω and a homomorphism h̄: *Fℤ → G such that h = h̄pF, where pF is the natural map from xωℤ into *Fℤ. Because of the corresponding phenomenon for abelian groups this is called the non-commutative Specker Phenomenon. In the present paper we shall show that Higman's result fails if one passes from countable to uncountable and thereby answer a question posed by K. Eda. In particular, we will see that, for an uncountable cardinal λ and for non-trivial groups Gx (α ∈ λ), there are 22λ homomorphisms from the free complete product of the groups Gx into the integers.
AB - Higman proved in 1952 that every free group is non-commutatively slender, that is, for a free group G and for a homomorphism h from the free complete product xωℤ of countably many copies of ℤ into G, there exists a finite subset F ⊆ ω and a homomorphism h̄: *Fℤ → G such that h = h̄pF, where pF is the natural map from xωℤ into *Fℤ. Because of the corresponding phenomenon for abelian groups this is called the non-commutative Specker Phenomenon. In the present paper we shall show that Higman's result fails if one passes from countable to uncountable and thereby answer a question posed by K. Eda. In particular, we will see that, for an uncountable cardinal λ and for non-trivial groups Gx (α ∈ λ), there are 22λ homomorphisms from the free complete product of the groups Gx into the integers.
UR - http://www.scopus.com/inward/record.url?scp=0347140873&partnerID=8YFLogxK
U2 - 10.1515/jgth.2001.031
DO - 10.1515/jgth.2001.031
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AN - SCOPUS:0347140873
SN - 1433-5883
VL - 4
SP - 417
EP - 426
JO - Journal of Group Theory
JF - Journal of Group Theory
IS - 4
ER -