文摘
We characterize ultrafilter convergence and ultrafilter compactness in linearly ordered and generalized ordered topological spaces. In such spaces, and for every ultrafilter D, the notions of D-compactness and of D-pseudocompactness are equivalent. Any product of initially λ-compact generalized ordered topological spaces is still initially λ-compact. On the other hand, preservation under products of certain compactness properties is independent from the usual axioms for set theory.KeywordsLinearly orderedGeneralized ordered topological spaceUltrafilter convergenceCompactnessPseudocompactness(pseudo-)gapConverging ν-sequence(weak) [ν, ν]-compactness(weak) initial λ-compactnessComplete accumulation pointλ-boundednessDecomposableDescendingly completeRegular ultrafilter