“…equivalence relation containing R, and since ∼ is the least such equivalence relation, we infer that (12) (s)…”
mentioning
confidence: 85%
“…But it is equal to µ r A * (G), which is positive. What we have just shown implies, by (7), that ϕ is a Stieltjes moment function. To see that it is Stieltjes determinate, it suffices to note that the semigroup S, being perfect, is determinate, hence trivially 'Stieltjes determinate'.…”
Section: But This Follows From (3) This Proves (6)mentioning
confidence: 99%
“…Every densely cosetlike semigroup is quasi-perfect [12]. It follows that a * -semigroup S is perfect if it is flat and (S) is densely cosetlike.…”
Section: Introductionmentioning
confidence: 99%
“…nx = y + z). If H is * -archimedean then every character on H is nowhere zero, so if H * separates points in H then H is cancellative [7]. A * -subsemigroup of a * -semigroup is a subsemigroup stable under the involution.…”
mentioning
confidence: 99%
“…Thus µ s is concentrated on G s . By (12) we infer that for each u ∈ U there is a unique complex measure µ u on A 0 (S *…”
“…equivalence relation containing R, and since ∼ is the least such equivalence relation, we infer that (12) (s)…”
mentioning
confidence: 85%
“…But it is equal to µ r A * (G), which is positive. What we have just shown implies, by (7), that ϕ is a Stieltjes moment function. To see that it is Stieltjes determinate, it suffices to note that the semigroup S, being perfect, is determinate, hence trivially 'Stieltjes determinate'.…”
Section: But This Follows From (3) This Proves (6)mentioning
confidence: 99%
“…Every densely cosetlike semigroup is quasi-perfect [12]. It follows that a * -semigroup S is perfect if it is flat and (S) is densely cosetlike.…”
Section: Introductionmentioning
confidence: 99%
“…nx = y + z). If H is * -archimedean then every character on H is nowhere zero, so if H * separates points in H then H is cancellative [7]. A * -subsemigroup of a * -semigroup is a subsemigroup stable under the involution.…”
mentioning
confidence: 99%
“…Thus µ s is concentrated on G s . By (12) we infer that for each u ∈ U there is a unique complex measure µ u on A 0 (S *…”
For every a > 1, there is a function f : N20 → R, which is positive semidefinite but not a moment sequence, such that |f(m, n)| ≥ m+ na(m+n) for all (m, n). The constant 1 is the best possible.
The problem of characterizing those semigroups of class ℳ︁ such that every positive definite function factors via the greatest C‐separative ∗︁‐homomorphic image is shown to be equivalent to several other problems, including that of characterizing flat semigroups. If the latter could be solved then the problem of characterizing perfect semigroups would be reduced to characterizing quasi‐perfect semigroups.
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