On powers of countably pracompact groups

In 1990, Comfort asked: is there, for every cardinal number α≤2c, a topological group G such that Gγ countably compact all cardinals γ<α, but Gα not compact? A similar question can also be asked pracompact groups: which α there pracompact? this paper we construct in the case α=ω, assuming existence of c incomparable selective ultrafilters, and α=κ+, with ω≤κ≤2c, 2c ultrafilters. particular, under second assumption, exists so G2c pracompact, G(2c)+ unlike case.