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On an affirmative answer to Y. Tanaka's and Y. Ge's problem

Luong Quoc Tuyen (2017)

Commentationes Mathematicae Universitatis Carolinae

In this paper, we give an affirmative answer to the problem posed by Y. Tanaka and Y. Ge (2006) in "Around quotient compact images of metric spaces, and symmetric spaces", Houston J. Math. 32 (2006) no. 1, 99-117.

On AP spaces in concern with compact-like sets and submaximality

Mi Ae Moon, Myung Hyun Cho, Junhui Kim (2011)

Commentationes Mathematicae Universitatis Carolinae

The definitions of AP and WAP were originated in categorical topology by A. Pultr and A. Tozzi, Equationally closed subframes and representation of quotient spaces, Cahiers Topologie Géom. Différentielle Catég. 34 (1993), no. 3, 167-183. In general, we have the implications: T 2 K C U S T 1 , where K C is defined as the property that every compact subset is closed and U S is defined as the property that every convergent sequence has at most one limit. And a space is called submaximal if every dense subset is open....

On FU( p )-spaces and p -sequential spaces

Salvador García-Ferreira (1991)

Commentationes Mathematicae Universitatis Carolinae

Following Kombarov we say that X is p -sequential, for p α * , if for every non-closed subset A of X there is f α X such that f ( α ) A and f ¯ ( p ) X A . This suggests the following definition due to Comfort and Savchenko, independently: X is a FU( p )-space if for every A X and every x A - there is a function f α A such that f ¯ ( p ) = x . It is not hard to see that p RK q ( RK denotes the Rudin–Keisler order) every p -sequential space is q -sequential every FU( p )-space is a FU( q )-space. We generalize the spaces S n to construct examples of p -sequential...

On minimal strongly KC-spaces

Weihua Sun, Yuming Xu, Ning Li (2009)

Czechoslovak Mathematical Journal

In this article we introduce the notion of strongly KC -spaces, that is, those spaces in which countably compact subsets are closed. We find they have good properties. We prove that a space ( X , τ ) is maximal countably compact if and only if it is minimal strongly KC , and apply this result to study some properties of minimal strongly KC -spaces, some of which are not possessed by minimal KC -spaces. We also give a positive answer to a question proposed by O. T. Alas and R. G. Wilson, who asked whether every...

On p -sequential p -compact spaces

Salvador García-Ferreira, Angel Tamariz-Mascarúa (1993)

Commentationes Mathematicae Universitatis Carolinae

It is shown that a space X is L ( μ p ) -Weakly Fréchet-Urysohn for p ω * iff it is L ( ν p ) -Weakly Fréchet-Urysohn for arbitrary μ , ν < ω 1 , where μ p is the μ -th left power of p and L ( q ) = { μ q : μ < ω 1 } for q ω * . We also prove that for p -compact spaces, p -sequentiality and the property of being a L ( ν p ) -Weakly Fréchet-Urysohn space with ν < ω 1 , are equivalent; consequently if X is p -compact and ν < ω 1 , then X is p -sequential iff X is ν p -sequential (Boldjiev and Malyhin gave, for each P -point p ω * , an example of a compact space X p which is 2 p -Fréchet-Urysohn and it is...

On pseudo-radial spaces

Aleksander V. Arhangel'skii, Romano Isler, Gino Tironi (1986)

Commentationes Mathematicae Universitatis Carolinae

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