November 1990
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3 Reads
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17 Citations
Topology and its Applications
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November 1990
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3 Reads
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17 Citations
Topology and its Applications
October 1990
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22 Reads
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49 Citations
Topology and its Applications
The normal Moore space conjecture asserts that normal Moore spaces are metrizable. Nyikos has proven the consistency (from the existence of a strongly compact cardinal) of the conjecture holding and Fleissner has proven that at least a measurable cardinal is needed to prove the consistency. Although extremely elegant, Nyikos' proof relies on Kunen's proof of the consistency of the product measure extension axiom and does not lend itself to other applications. In this paper we first present the groundwork for iterated forcing and reflection type proofs from the assumption of a supercompact cardinal. We then use this technology to give a proof of the normal Moore space conjecture as well as several other similar results which use a variation of the proof.
June 1990
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11 Reads
Topology and its Applications
In this article, it is shown to be consistent that is not C∗-embedded in βω2. It is also shown that if the existence of a weakly compact cardinal is consistent with ZFC, then so is the negation of the previous statement. Furthermore, both results are independent of CH.
January 1990
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2 Reads
Topology and its Applications
June 1989
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19 Reads
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7 Citations
Israel Journal of Mathematics
We determine those regular cardinals κ with the property that for each increasing κ-chain of first countable spaces there is a compatible first countable topology on the union of the chain. AssumingV=L any such κ must be weakly compact. It is relatively consistent with a supercompact cardinal that each κ>w 1 has the property. The proofs exploit the connection with interesting families of integer-valued functions.
March 1989
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5 Reads
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12 Citations
Transactions of the American Mathematical Society
In the model obtained by adding side-by-side Sacks reals to a model of CH, there is a separable nonpseudocompact space with no remote points. To prove this it is also shown that in this model the countable box product of Cantor sets contains a subspace of size such that every uncountable subset has density . Furthermore assuming the existence of a measurable cardinal with , a space X is produced with no isolated points but with remote points in . It is also shown that a pseudocompact space does not have remote points.
January 1989
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7 Reads
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4 Citations
Transactions of the American Mathematical Society
In the model obtained by adding ω 2 {\omega _2} side-by-side Sacks reals to a model of C H {\mathbf {CH}} , there is a separable nonpseudocompact space with no remote points. To prove this it is also shown that in this model the countable box product of Cantor sets contains a subspace of size ω 2 {\omega _2} such that every uncountable subset has density ω 1 {\omega _1} . Furthermore assuming the existence of a measurable cardinal κ \kappa with 2 κ = κ + {2^\kappa } = {\kappa ^ + } , a space X X is produced with no isolated points but with remote points in υ X − X \upsilon X - X . It is also shown that a pseudocompact space does not have remote points.
December 1988
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4 Reads
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5 Citations
Proceedings of the American Mathematical Society
Examples of products with remote points and counterexamples of products without remote points are given. The paradoxical behavior of remote points with respect to products is exhibited. Also, an example is given of spaces X and Y, where neither X nor Y has a σ-locally finite π-base, but X×Y does.
December 1987
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5 Reads
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4 Citations
Topology and its Applications
It is shown that a product of metric spaces has remote points if and only if it is noncompact. Within the proof, infinitary combinatoric methods are developed and implemented to create an effective strategy for a two player game. Many new examples are given of nonpseudocompact products which have the property that the nonhomogeneity of the remainder can be demonstrated by an explicit pair of points.
... A theorems follows. The following was proved in [5] Theorem { [5]). Assume that pei>X\X is a remote point of X and 17_ consists of cozero-sets in X. ...
January 1989
Transactions of the American Mathematical Society
... A point y ∈ β(X)\X is remote if and only if the trace of N (y) on X is an open ultrafilter [4]. See [2,7,9,10,11,12,39,42] for more about remote points and their applications to non-homogeneity and butterfly points of Cech-Stone compactifications. ...
Reference:
Open filters and measurable cardinals
March 1989
Transactions of the American Mathematical Society
... A point y ∈ β(X)\X is remote if and only if the trace of N (y) on X is an open ultrafilter [4]. See [2,7,9,10,11,12,39,42] for more about remote points and their applications to non-homogeneity and butterfly points of Cech-Stone compactifications. ...
Reference:
Open filters and measurable cardinals
December 1988
Proceedings of the American Mathematical Society
... Alan's proof that ω × 2 κ has remote points gave new insight in the structure of the partial order that adds Cohen reals: a remote point, seen as a clopen filter on ω × 2 κ , takes big bites out of dense open sets and these bites combine to form approximations of generic filters, called enDowments by some. These enDowments were crucial in a Cohen-real proof of the consistency of the normal Moore space conjecture, [10,11]. We must also mention that Alan showed that the result of Fine and Gillman needs extra assumptions: in the side-by-side Sacks model there is a non-pseudocompact separable space without remote points, [8]. ...
Reference:
Alan Dow
November 1990
Topology and its Applications
... Marun ([18]) showed in his PhD thesis -both earlier and independently of [7] -that posets which are strongly proper for enough countable elementary submodels preserve the Lindelöf property. Some other noteworthy examples in this line of research include the following: [4], [5], [10], and [?]. ...
October 1990
Topology and its Applications