@ARTICLE {TP28.2.01, AUTHOR = {Auslander, Joseph}, TITLE = {A group theoretic condition in topological dynamics}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {327--334}, URL = {http://at.yorku.ca/b/a/a/m/28.htm}, MRCLASS = {37B05}, KEYWORDS = {Minimal flow, regionally proximal relation}, ABSTRACT = {We relate group theoretic conditions to regional proximality in minimal flows. A generalization of a theorem of the author and Robert and David Ellis is obtained.}, } @ARTICLE {TP28.2.02, AUTHOR = {Berestovskii, Valera and Plaut, Conrad}, TITLE = {The universal cover of the quotient of a locally defined group}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {335--342}, URL = {http://at.yorku.ca/b/a/a/m/29.htm}, MRCLASS = {22A05 (46A99 55Q05)}, KEYWORDS = {Universal cover, topological vector space}, ABSTRACT = {We present a new method to compute the (generalized) universal cover of a quotient $V/G$ of a locally defined group $V$ via a closed subgroup $G$, and give some applications. For example we show that if $G$ is locally generated (e.g.\ if $G$ is connected) then $V/G$ is locally defined. We give some answers to the question of when the universal cover of a quotient of a topological vector spaces is again a topological vector space.}, } @ARTICLE {TP28.2.03, AUTHOR = {Bouziad, A. and Troallic, J.-P.}, TITLE = {Nonseparability and uniformities in topological groups}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {343--359}, URL = {http://at.yorku.ca/b/a/a/m/30.htm}, MRCLASS = {22A05 54E15 (22A10)}, KEYWORDS = {Topological group, Left (right) uniform structure, Left (right) uniformly continuous bounded real-valued function, SIN-group, FSIN-group, Left (right) thin subset, Left (right) neutral subset, Left (right) uniformly discrete subset}, ABSTRACT = {Let $G$ be a Hausdorff topological group. If the left and right uniform structures $\mathcal{L}_G$ and $\mathcal{R}_G$ on $G$ coincide, then $G$ is said to be balanced, or a SIN-group. Let $\mathcal{U}_L(G)$ (respectively $\mathcal{U}_R(G)$) denote the real Banach space of all left (respectively right) uniformly continuous bounded real-valued functions on $G$, and let $\mathcal{U}(G) = \mathcal{U}_L(G)\cap\mathcal{U}_R(G)$. If $\mathcal{U}_L(G) = \mathcal{U}_R(G)$, then $G$ is said to be functionally balanced, or to be an FSIN-group. We prove that if $G$ is not an FSIN-group, then the quotient Banach space $\mathcal{U}_R(G)/\mathcal{U}(G)$ is nonseparable. Moreover, we prove that for a large class of topological groups $G$, if $G$ is not FSIN then $\mathcal{U}_R(G)/\mathcal{U}(G)$ contains a linear isometric copy of $l^{\infty}$. We also establish the equivalence between SIN and FSIN properties in various cases. In particular, we show that for any topological group $G$ strongly functionally generated by its right precompact subsets, SIN and FSIN properties are equivalent.}, } @ARTICLE {TP28.2.04, AUTHOR = {Carlson, Timothy J. and Hindman, Neil and Strauss, Dona}, TITLE = {The {G}raham-{R}othschild {T}heorem and the algebra of $\beta{W}$}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {361--399}, URL = {http://at.yorku.ca/b/a/a/m/31.htm}, MRCLASS = {54D35 (54H15 05D10)}, KEYWORDS = {Graham-Rothschild Theorem, variable words, free semigroup, Stone-\v{C}ech compactification}, ABSTRACT = {In a previous paper we established an infinitary extension of the Graham-Rothschild Theorem by producing an infinite decreasing chain of idempotents in the Stone-\v{C}ech compactification of the set of variable words over a nonempty alphabet. In this paper we investigate further the algebraic structure of that compactification and determine which finite chains of idempotents are extendable to an infinite chain as above.}, } @ARTICLE {TP28.2.05, AUTHOR = {Comfort, W. W.}, TITLE = {Tampering with pseudocompact groups}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {401--424}, URL = {http://at.yorku.ca/b/a/a/m/32.htm}, MRCLASS = {54H11 22A05 (22-02 54-02)}, KEYWORDS = {Compact group, countably compact group, $\omega$-bounded group, pseudocompact group, totally bounded group. free topological group, free Abelian topological group. refinement topology, dense subgroup. extremal pseudocompact topological group}, ABSTRACT = {This paper is an extended version of the Invited Address presented by the author at the 2003 Summer Conference on General Topology and Its Applications (Howard University, Washington, DC). Let $\mathbb{C}$, $\Omega$, $\mathbb{C}\mathbb{C}$, $\mathbb{P}$ and $\mathbb{T}\mathbb{B}$ denote, respectively, the class of Hausdorff topological groups which are compact, $\omega$-bounded, countably compact, pseudocompact, and totally bounded, and let $\mathbb{X}$, $\mathbb{Y}$ in $\{$ $\mathbb{C}$, $\Omega$, $\mathbb{C}\mathbb{C}$, $\mathbb{P}$, $\mathbb{T}\mathbb{B}$ $\}$. In {\it Part I} the author attempts a survey of the literature concerning the following $5 + (2 \times 5 \times 5) = 55$ questions and their Abelian analogues: 1.~Is there an algebraic characterization of those groups $G$ which admit a group topology $\mathcal{T}$ such that $(G,\mathcal{T}) \in \mathbb{X}$? 2.~If $(G,\mathcal{T}) \in \mathbb{X}$, does $G$ admit a proper dense subgroup $H \in \mathbb{Y}$? 3.~If $(G,\mathcal{T}) \in \mathbb{X}$ does $G$ admit a group topology $\mathcal{S}$, properly refining $\mathcal{T}$, such that $(G,\mathcal{S}) \in \mathbb{Y}$? Emphasis is both on what is known and on some of the most attractive or compelling unsolved questions. {\it Part II} studies more intensively the extensive literature concerning Questions~2 and 3 in the case that $\mathbb{X}$ and $\mathbb{Y}$ are the class of nonmetrizable pseudocompact (Abelian) groups. Not even a ZFC-consistent answer is known in either case, but the questions are shown to be unexpectedly related. Most of the new results cited derive from (as yet unpublished) joint work with Jorge Galindo.}, } @ARTICLE {TP28.2.06, AUTHOR = {Comfort, W.W. and Hager, A.W.}, TITLE = {Maximal realcompact (and other) topologies}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {425--443}, URL = {http://at.yorku.ca/b/a/a/m/33.htm}, MRCLASS = {04A10 54A25 54B30 54D35 54D10 54G10 18A40 18B30}, KEYWORDS = {Maximal topology, measurable cardinal, epireflection, coreflection, realcompact space, $P$-space}, ABSTRACT = {Let $\mathbf{R}\mathbf{C}$ be the class of realcompact Tychonoff spaces, $\mathfrak{m}$ the first uncountable measurable cardinal (which is the first Ulam measurable cardinal), and $\mathbf{P}(\mathfrak{m})$ the class of spaces in which each intersection of fewer than $\mathfrak{m}$ open sets is open. We begin with a simple theorem: If $X \in \mathbf{R}\mathbf{C}$, there is another space $\mu X$ on the same set as $X$ whose topology is maximum for being $\mathbf{R}\mathbf{C}$ and finer than the topology of $X$. (Of course, $\mu X$ is discrete if and only if $|X|<\mathfrak{m}$.) This gives an operator $\mu\colon \mathbf{R}\mathbf{C} \to \mathbf{M} := \{X : \mu X=X\}$ which is a coreflection. It is known that the $\mathbf{P}(\mathfrak{m})$-coreflection preserves $\mathbf{R}\mathbf{C}$; thus $\mathbf{M} \subseteq \mathbf{P}(\mathfrak{m}) \cap \mathbf{R}\mathbf{C}$. The reverse inclusion represents an open question [Alan Dow has shown that this is undecidable. See the note at the end of this paper], but we prove it for two classes of spaces: Those for which the pseudocharacter does not exceed $\mathfrak{m}$, and those with fewer than $\mathfrak{m}$ nonisolated points. Various examples of spaces in $\mathbf{M}$ are presented, indeed: for every cardinal number $\mathfrak{n}$ there are spaces in $\mathbf{M}$ with exactly $\mathfrak{n}$ nonisolated points. Actually, these observations about $\mathbf{R}\mathbf{C}$ and $\mathfrak{m}$ are but a special case. In the previous paragraph we may replace $\mathbf{R}\mathbf{C}$ by any class $\mathbf{R}$ which is productive and closed-hereditary and contains the two-point space, while replacing $\mathfrak{m}$ by $\sigma(\mathbf{R}) := \sup\{\kappa : \text{$\mathbf{R}$ contains the discrete space with $\kappa$ points}\}$ (which, it is known, is a measurable cardinal if not $\infty$).}, } @ARTICLE {TP28.2.07, AUTHOR = {Dolecki, Szymon}, TITLE = {Elimination of covers in completeness}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {445--465}, URL = {http://at.yorku.ca/b/a/a/m/34.htm}, MRCLASS = {54A20 54D99}, KEYWORDS = {\v{C}ech completeness}, ABSTRACT = {It is shown that nonadherent filters can totally eliminate covers from topological arguments, which enhances the unity of convergence approach. In particular, cocomplete collections of nonadherent filters replace complete collections of covers. Arhangel'skii-Frol\'ik characterization of \v{C}ech complete spaces and its generalizations by Frol\'ik are extended and refined. Hereditary completeness is dually characterized (in terms of pavements of the upper Kuratowski convergence). As a corollary a characterization by Dolecki and Mynard of the pretopologicity of the upper Kuratowski convergence (which generalizes to arbitrary convergences the characterization of Hofmann and Lawson) is recovered.}, } @ARTICLE {TP28.2.08, AUTHOR = {Galindo, Jorge}, TITLE = {Totally bounded group topologies that are Bohr topologies of LCA groups}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {467--478}, URL = {http://at.yorku.ca/b/a/a/m/35.htm}, MRCLASS = {54H11 22A05}, KEYWORDS = {Bohr topology, locally compact Abelian group, k-extension, totally bounded}, ABSTRACT = {Some conditions that are obviously necessary for a totally bounded group to be the Bohr group of a locally compact Abelian group are shown to be sufficient.}, } @ARTICLE {TP28.2.09, AUTHOR = {Gl\"ockner, Helge}, TITLE = {Examples of differentiable mappings into non-locally convex spaces}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {479--486}, URL = {http://at.yorku.ca/b/a/a/m/36.htm}, MRCLASS = {58C20 (26E20 46A16 46G20)}, KEYWORDS = {Differentiable mappings, Taylor series, Fundamental Theorem of Calculus, non-locally convex spaces}, ABSTRACT = {Examples of differentiable mappings into real or complex topological vector spaces with specific properties are given, which illustrate the differences between differential calculus in the locally convex and the non-locally convex case.}, } @ARTICLE {TP28.2.10, AUTHOR = {Gotchev, Ivan and Minchev, Hristo}, TITLE = {On sequential properties of {N}oetherian topological spaces}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {487--581}, URL = {http://at.yorku.ca/b/a/a/m/37.htm}, MRCLASS = {54D55 54D20 13E05 (54D30 54D10 54A10)}, KEYWORDS = {Noetherian ring, Noetherian topological space, Zariski space, sequentially compact, s-compact, compact, sequential space}, ABSTRACT = {Sequential properties of Noetherian topological spaces are considered. A topological space $X$ is called \emph{Noetherian} if for every increasing by inclusion sequence $(U_n)_{n=1}^\infty$ of open subsets of $X$ there exists $n$ such that $U_n = U_{n+1} = \ldots$. It is shown that every Noetherian topological space is sequentially compact and that the sequential topology inherits the Noetherian property. Hence, every sequentially open cover of a Noetherian topological space has a finite subcover. The following result is proved: Let $X$ be a Noetherian topological space in which every irreducible closed subset $F$ has a generic point. The space $X$ is sequential if and only if $h(X) \leq \omega_1$, where $h(X)$ is a suitable ordinal invariant. From this result follows that a Zariski space $X$ is sequential if and only if $h(X) \leq \omega_1$ and that if $R$ is a commutative Noetherian ring then the prime spectrum ${\mathrm Spec} R$ is a sequential Noetherian topological space.}, } @ARTICLE {TP28.2.11, AUTHOR = {Hattab, H. and Salhi, E.}, TITLE = {Groups of homeomorphisms and spectral topology}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {503--526}, URL = {http://at.yorku.ca/b/a/a/m/38.htm}, MRCLASS = {57R30 57S05}, KEYWORDS = {Groups of homeomorphisms, quasi-orbits space, A.F. $C^*$-algebra, unit ary commutative ring}, ABSTRACT = {The aim of this paper is to study some of the relationships between groups of homeomorphisms on one side, and approximately finite-dimensional (A.F.) $C^*$-algebra, unitary commutative ring on the other side. Let $G$ be a countable group of homeomorphisms of a locally compact second countable topological space $E$. The class of an orbit $O$ is the union of all orbits $O'$ having the same closure as $O$. We denote by $X$ the quasi-orbits space (i.e.\ the space of orbits classes). If every decreasing sequence of saturated closed subsets of $E$ is finite, then $X$ is homeomorphic to the prime spectrum of a unitary commutative ring equipped with the Zariski topology and $E$ is the closure of the union of a finitely many orbits. Let $E$ be the line $\mathbb{R}$ such that every element of $G$ is an increasing homeomorphism and let $X_0$ be the union of all open subsets of $X$ homeomorphic to $\mathbb{R}$ or $S^1$. The space $X-X_0$ is always homeomorphic to the primitive spectrum of an A.F. $C^*$-algebra equipped with the Jacobson topology and if $G$ has a minimal set, then it is homeomorphic to the prime spectrum of a unitary commutative ring equipped with the Zariski topology if and only if every totally ordered family of orbits has a greatest lower bound. We give an example of a diffeomorphism of the unit 2-sphere $S^2$ such that the above result fails.}, } @ARTICLE {TP28.2.12, AUTHOR = {Hern\'andez, Salvador}, TITLE = {Extension of continuous functions on product spaces, {B}ohr compactification and almost periodic functions}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {527--540}, URL = {http://at.yorku.ca/b/a/a/m/39.htm}, MRCLASS = {05C38 15A15 (05A15 15A18)}, KEYWORDS = {Bohr compactification, almost periodic functions, product spaces, extension of continuous functions}, ABSTRACT = {The Bohr compactification is a well known construction for (topological) groups and semigroups. Recently, this notion has been investigated for arbitrary structures in [K. Kunen and J. Hart, Fund. Math. (1999)] where the Bohr compactification is defined, using a set-theoretical approach, as the maximal compactification which is compatible with the structure involved. Here, we give a characterization of the continuous functions defined on a product space that can be extended continuously to certain compactifications of the product space. As a consequence, the Bohr compactification of an arbitrary topological structure is obtained as the Gelfand space of the commutative Banach algebra of all almost periodic functions. Previously, almost periodic functions $f$ are defined in terms of translates of $f$ with no reference to any compactification of the underlying structure. An application is given to the representation of isometries defined between spaces of almost periodic functions.}, } @ARTICLE {TP28.2.13, AUTHOR = {Hofmann, Karl H. and Morris, Sindey A.}, TITLE = {Lie theory and the structure of pro-{L}ie groups and pro-{L}ie algebras}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {541--567}, URL = {http://at.yorku.ca/b/a/a/m/40.htm}, MRCLASS = {22Dxx 22Exx}, KEYWORDS = {Lie group, projective limit, Lie algebra, exponential function, locally compact group, pro-Lie algebra, simply connected group, abelian pro-Lie group}, ABSTRACT = {This text presents basic results from a projected monograph on ``Lie Theory and the Structure of Pro-Lie groups and Locally Compact Groups'' which may be considered a sequel to our book ``The Structure of Compact Groups'' [De Gruyter, Berlin, 1998]. In focus are the categories of projective limits of finite dimensional Lie groups and of projective limits of finite dimensional Lie algebras, their functorial relationship, and their intrinsic Lie theory. Explicit information on pro-Lie algebras, simply connected pro-Lie groups and abelian pro-Lie groups is given.}, } @ARTICLE {TP28.2.14, AUTHOR = {Itzkowitz, Gerald}, TITLE = {Functional balance, discrete balance, and balance in topological groups}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {569--577}, URL = {http://at.yorku.ca/b/a/a/m/41.htm}, MRCLASS = {22C05 22A05 54A25 54B05 54B10 54B15}, KEYWORDS = {$T_{0}$ topological group, uniform space, uniformly continuous function, uniform separation, functionally uniformly separated, left uniformity, right uniformity, balanced group, left uniformly continuous function, right uniformly continuous function, functionally balanced group, left uniformly discrete set, right uniformly discrete set, discretely balanced group, strongly uniformly discrete}, ABSTRACT = {We consider the question of determining parameters for when topological group balance (the left and right uniformities on the group are equivalent) and functional balance (the classes of left and right uniformly continuous bounded real valued functions coincide) in topological groups are equivalent. Our main result is that a topological group $G$ is balanced iff it is functionally balanced and discretely balanced. A topological group is discretely balanced if every left uniformly discrete subset is right uniformly discrete. This partially answers a question of T.S. Wu. The proof makes use of a theorem derived from the well known theorem of Katetov on extending real valued bounded uniformly continuous functions from a subspace of a uniform space to the whole space and a characterization of uniform separation pointed out by the author in a previous paper. It is still unknown if the conditions that $G$ is balanced and $G$ is functionally balanced are equivalent.}, } @ARTICLE {TP28.2.15, AUTHOR = {Karasev, A. V.}, TITLE = {The {U}rysohn identity for closed subsets of some nonmetrizable manifolds}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {579--585}, URL = {http://at.yorku.ca/b/a/a/m/42.htm}, MRCLASS = {54F45 (55M10)}, KEYWORDS = {Inductive dimension, nonmetrizable manifold, Martin's axiom}, ABSTRACT = {Let $Y$ be a closed subspace of $M\times L$ where $M$ is a compact manifold and $L$ is the long line. Assuming Martin's axiom and the negation of continuum hypothesis, we prove that ${\mathrm ind} Y = {\mathrm dim} Y = {\mathrm Ind} Y$.}, } @ARTICLE {TP28.2.16, AUTHOR = {Kato, Hisao}, TITLE = {Topological entropy of monotone maps and confluent maps on regular curves}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {587--593}, URL = {http://at.yorku.ca/b/a/a/m/43.htm}, MRCLASS = {54C70 54F20 54H20 (37E25 37B40)}, ABSTRACT = {G.T. Seidler proved that the topological entropy of every homeomorphism on a regular curve is zero. L.S. Efremova and E.N. Markhrova proved that the topological entropy of every monotone map on a dendrite which satisfies some special condition is zero. N. Chinen proved that the topological entropy of every monotone map on any dendrite is zero. In this paper, we generalize these results. In fact, we investigate the topological entropy of confluent maps on regular curves. As a corollary, we show that the topological entropy of every monotone map on any regular curve is zero.}, } @ARTICLE {TP28.2.17, AUTHOR = {Koppelberg, Sabine}, TITLE = {The {H}ales-{J}ewett theorem via retractions}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {595--601}, URL = {http://at.yorku.ca/b/a/a/m/44.htm}, MRCLASS = {05D10 (22A15)}, KEYWORDS = {Stone-\v{C}ech compactification, Hales-Jewett theorem}, ABSTRACT = {Working in the Stone-\v{C}ech compactification of an arbitrary semigroup, we prove an abstract version of the Hales-Jewett theorem. We easily obtain the classical Hales-Jewett theorem, van der Waerden's theorem and Gallai's theorem as special cases. We observe that our abstract version of the Hales-Jewett theorem can be derived from the classical one.}, } @ARTICLE {TP28.2.18, AUTHOR = {Kubi\'s, Wies{\l}aw and Leiderman, Arkady}, TITLE = {Semi-{E}berlein spaces}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {603--616}, URL = {http://at.yorku.ca/b/a/a/m/45.htm}, MRCLASS = {54D30 (54C35 54C10)}, KEYWORDS = {Semi-Eberlein space, Valdivia/Corson compact, semi-open retraction}, ABSTRACT = {We investigate the class of compact spaces which are embeddable into a power of the real line $\mathbb{R}^\kappa$ in such a way that $c_0(\kappa) = \{ f \in \mathbb{R}^\kappa : (\forall \epsilon > 0) \left|\{\alpha \in \kappa : |f(\alpha)| > \epsilon\}\right| < \aleph_0\}$ is dense in the image. We show that this is a proper subclass of the class of Valdivia, even when restricted to Corson compacta. We prove a preservation result concerning inverse sequences with semi-open retractions. As a corollary we obtain that retracts of Cantor or Tikhonov cubes belong to the above class.}, } @ARTICLE {TP28.2.19, AUTHOR = {McCutcheon, Randall}, TITLE = {Rhythmic functions and {I}{P} recurrence}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {617--637}, URL = {http://at.yorku.ca/b/a/a/m/46.htm}, MRCLASS = {11J25 (37B20)}, KEYWORDS = {Minimality, distality, rhythmicity, IP recurrence, syndeticity, VIP systems, Diophantine approximation}, ABSTRACT = {Various classes of functions arising in the study of a problem in Diophantine approximation are studied. Chief among these are so-called rhythmic functions, as defined analytically by J. van der Corput, and IP recurrent functions, as defined analytically by H. Furstenberg and B. Weiss. Equivalent definitions for these classes are given in the language of topological dynamics, and strong parallels are observed in consequence. A recently developed alternative method for attacking the underlying Diophantine approximation problem is mentioned, with new results thereby obtained.}, } @ARTICLE {TP28.2.20, AUTHOR = {M\'{e}ndez-Lango, H\'{e}ctor}, TITLE = {The process of finding $f^{\prime}$ for an entire function $f$ has infinite topological entropy}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {639--646}, URL = {http://at.yorku.ca/b/a/a/m/47.htm}, MRCLASS = {54H20 37B40}, KEYWORDS = {Topological entropy, chaotic maps}, ABSTRACT = {Let $(H(\mathbb{C}), \rho)$ be the metric space of all entire functions $f$ where the metric $\rho$ induces the topology of uniform convergence on compact subsets of the complex plane. Let $D\colon H(\mathbb{C}) \to H(\mathbb{C})$ be the linear mapping that assigns to each $f$ its derivative, $D(f) = f^\prime$. We show in this note that there exists a compact subset of $H(\mathbb{C})$, say $K$, that is invariant under $D$, and $D$ restricted to $K$ has infinite topological entropy.}, } @ARTICLE {TP28.2.21, AUTHOR = {Previts, W.H. and Wu, T.S.}, TITLE = {Notes on tidy subgroups of locally compact totally disconnected groups}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {647--654}, URL = {http://at.yorku.ca/b/a/a/m/48.htm}, MRCLASS = {22D05}, KEYWORDS = {Locally compact totally disconnected group, tidy subgroup, automorphism}, ABSTRACT = {Willis established a structure theory of locally compact totally disconnected groups. An important feature of his theory is the notion of a tidy subgroup. In this note we provide results regarding these subgroups.}, } @ARTICLE {TP28.2.22, AUTHOR = {Stojmirovi\'c, Aleksandar}, TITLE = {Quasi-metric spaces with measure}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {655--671}, URL = {http://at.yorku.ca/b/a/a/m/49.htm}, MRCLASS = {54E55, 28C15 (92C40)}, KEYWORDS = {quasi-metrics, concentration of measure, biological sequences}, ABSTRACT = {The phenomenon of concentration of measure on high dimensional structures is usually stated in terms of a metric space with a Borel measure, also called an mm-space. We extend some of the mm-space concepts to the setting of a quasi-metric space with probability measure (pq-space). Our motivation comes from biological sequence comparison: we show that many common similarity measures on biological sequences can be converted to quasi-metrics. We show that a high dimensional pq-space is very close to being an mm-space.}, } @ARTICLE {TP28.2.23, AUTHOR = {Tsuiki, Hideki}, TITLE = {Dyadic subbases and efficiency properties of the induced $\{0,1,\bot\}^\omega$-representations}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {673--687}, URL = {http://at.yorku.ca/b/a/a/m/50.htm}, MRCLASS = {54H99 (68R99)}, KEYWORDS = {Plotkin's $\mathbb{T}^{\omega}$, Gray code, Tent function, Dyadic subbase, Independent subbase, Minimal subbase, Canonically representing subbase}, ABSTRACT = {A dyadic subbase induces a representation of a second-countable regular space as a subspace of the space of infinite sequences of $\{0,1,\bot\}$, which is known as Plotkin's $\mathbb{T}^{\omega}$. We study four properties of dyadic subbases---full-representing, canonically representing, independent, and minimal---which express efficiency properties of the induced representations.}, } @ARTICLE {TP28.2.24, AUTHOR = {van Mill, Jan}, TITLE = {A note on {F}ord's example}, ISSN = {0146-4124}, JOURNAL = {Topology Proc.}, VOLUME = {28}, YEAR = {2004}, NUMBER = {2}, PAGES = {689--694}, URL = {http://at.yorku.ca/b/a/a/m/51.htm}, MRCLASS = {54H15}, KEYWORDS = {Homogeneous space, coset space, transitive action, compactification}, ABSTRACT = {Ford gave an example of a homogeneous space that is not a coset space. This example is not metrizable. We present a separable metrizable space with similar properties.}, }