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113. Pták homomorphism theorem revisited

Creator:
Ferrer, J. R. , López Pellicer, M., and Ruiz, L. M. Sánchez
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
math, homomorphism theorem B-complete space, and B-complete space
Language:
English
Description:
Rodrigues’ extension (1989) of the classical Pták’s homomorphism theorem to a non-necessarily locally convex setting stated that a nearly semi-open mapping between a semi-B-complete space and an arbitrary topological vector space is semi-open. In this paper we study this extension and, as a consequence of the results obtained, provide an improvement of Pták’s homomorphism theorem.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

117. Remarks on Steinhaus’ property and ratio sets of sets of positive integers

Creator:
Šalát, Tibor
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
math and sets of positive integers
Language:
English
Description:
This paper is closely related to an earlier paper of the author and W. Narkiewicz (cf. [7]) and to some papers concerning ratio sets of positive integers (cf. [4], [5], [12], [13], [14]). The paper contains some new results completing results of the mentioned papers. Among other things a characterization of the Steinhaus property of sets of positive integers is given here by using the concept of ratio sets of positive integers.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public