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Mostafa Ghadermazi

Mostafa Ghadermazi

Academic rank: Assistant Professor
ORCID:
Education: PhD.
ScopusId: 45613
Faculty: Faculty of Science
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Research

Title
C(X) Versus its Functionally Countable Subalgebra
Type
JournalPaper
Keywords
Functionally countable subring · Socle · zc-ideal · Regular ring · CP-space
Year
2019
Journal Bulletin of the Iranian Mathematical Society
DOI
Researchers Mostafa Ghadermazi ، Omid ali shahni karamzadeh ، Mehrdad namdari

Abstract

Abstract Let Cc(X) (resp. CF (X)) denote the subring of C(X) consisting of functions with countable (resp. finite) image and CF (X) be the socle of C(X). We characterize spaces X with C∗(X) = Cc(X), which generalizes a celebrated result due to Rudin, Pelczynnski, and Semadeni. Two ( zero-dimensional compact spaces X, Y are homeomorphic if and only if Cc(X)∼=Cc(Y ) .(resp. CF (X)∼=CF (Y ) The spaces X for which Cc(X) = CF (X) are characterized. The socles of Cc(X) (resp. C CF (X), which are observed to be the same, are topologically characterized and spaces X for which this socle coincides with C^*F (X) are determined, too. A certain well-known lgebraic property of C(X), where X is real compact, is extended to Cc(X). In contrast to the fact that CF (X) is never prime in C(X), we characterize spaces X for which CF (X) is a prime ideal in Cc(X). It is observed for these spaces, Cc(X) coincides with its own socle (a fact, which is never true for C(X), unless X is finite). Finally, we show that a space X is the one-point compactification of a discrete space if and only if C^*F (X) is a unique proper essential ideal in .(C^*F (X