A Note on a Paper of J. D. Stein, Jr

Among other results, it is proved that if a sequence {t 1l) of regular measures on a Hausdorff space, with values in a normed group, is convergent to zero for all a-compact sets or all open sets, then there exists a maximal open set U such that ft,1 ( U) O-* { f t,) being the associated submeasures. In [5], J. D. Stein, Jr. considers some versions of Phillip's lemma and the Vitali-Hahn-Saks theorem for sequences of regular scalar-valued Borel measures on Hausdorff spaces. The measures he considers are bounded, regular, and finitely additive Borel measures which are easily seen to be countably additive (to prove this, first note that I pi, the variation of such a measure /L, is regular, bounded, and finitely additive [5, Lemma 1]) and so for a sequence {Bi) of Borel sets, B1j0, and > 0, C a sequence of compact sets (Ki), Ki c Bi and vi(Bi \ K1) some no and so I til(BiWO), an observation which enables one to prove his results easily, in more general forms, and under weaker conditions. Theory of submeasures developed in [1] will be used. Let G be an Abelian Hausdorff topological group, X a Hausdorff topological space, and yt a countably additive, regular, G-valued measure on X (by regularity we mean that for any Borel set B in X and a 0-nbd U in G, there exists a compact set C c B such that tt(K) C U, VK c B \ C, K Borel). If G is normed [1, p. 270], we have an associated submeasure ft, AK(B) = sup{14(A)I:A c B,A Borel) = sup{ I(C)I: C c B, Ccompact), which is finite [1, p. 279, Corollary 4.1 1], exhaustive, a-subadditive, and order-continuous [1, II]. It is also regular in the sense that given E > 0 and a Borel set B, 3 a compact set K c B such that i(B \ K) < (proof by contradiction, using exhaustivity). For a collection of measures or subReceived by the editors August 25, 1976. AMS (MOS) subject classifications (1970). Primary 28A25; Secondary 46G10.