The structure of graphs all of whose Y-sections are internal sets

1991 ◽  
Vol 56 (1) ◽  
pp. 50-66 ◽  
Author(s):  
Boško Živaljević
Keyword(s):  
The Other ◽  
Topological Spaces ◽  
Structural Result ◽  
Other Hand ◽  
Small Cardinality ◽  
Borel Functions ◽  
Internal Function ◽  
Internal Sets

The purpose of this paper is to give structural results on graphs lying in the product of two hyperfinite sets X and Y, whose Y-sections are either all internal sets or all of “small” cardinality with respect to the saturation assumption imposed on our nonstandard universe. These results generalize those of [KKML] and [HeRo]. In [KKML] Keisler, Kunen, Miller and Leth proved, among other results, that any countably determined function in the product of two internal sets X and Y can be covered by countably many internal functions provided that the nonstandard universe is at least ℵ-saturated. This shows that any countably determined function can be represented as a union of countably many restrictions of internal functions to countably determined sets. On the other hand, Henson and Ross use in [HeRo] Choquet's capacitability theorem to prove that any Souslin function in the product of two internal sets X and Y is a.e. equal to an internal function. (Here “a.e.” refers to an arbitrary but fixed bounded Loeb measure.) Therefore, in our terminology, every Souslin function possesses an internal a.e. lifting.After the introductory §0, where all the necessary terminology is introduced, we continue by presenting the structural result for graphs all of whose Y-sections are of cardinality ≤κ (provided that the nonstandard universe is ≤κ+-saturated) in §1. We show that, under the above saturation assumption, a κ-determined graph with all of the Y-sections of cardinality ≤κ is covered by κ-many internal functions. Therefore, any such graph is a union of κ-many κ-determined functions. In particular if the graph in question is Borel, Souslin, κ-Borel or κ-Souslin (or a member of one of the Borel, κ-Borel or projective hierarchies) then the corresponding constituting functions are of the same “complexity”. Thus, any Borel graph all of whose Y-sections are at most countable is a union of countably many Borel functions and, consequently, has Borel domain. In the setting of Polish topological spaces this was proved by Novikov (see [De]).

Postnikov “Invariants” in 2004

2005 ◽  
Vol 12 (1) ◽  
pp. 139-155
Author(s):  
Julio Rubio ◽  
Francis Sergeraert
Keyword(s):  
Decision Problem ◽  
The Other ◽  
Topological Spaces ◽  
Exact Nature ◽  
Other Hand

Abstract The very nature of the so-called Postnikov invariants is carefully studied. Two functors, precisely defined, explain the exact nature of the connection between the category of topological spaces and the category of Postnikov towers. On one hand, these functors are in particular effective and lead to concrete machine computations through the general machine program Kenzo. On the other hand, the Postnikov “invariants” will be actual invariants only when an arithmetical decision problem – currently open – will be solved; it is even possible this problem is undecidable.

scholarly journals Weakly b-Closed Sets and Weakly b-Open Sets based of Fuzzy Neutrosophic bi-Topological Spaces

2020 ◽  
pp. 34-43
Author(s):  
Fatimah M. .. ◽  
◽  
◽  
Sarah W. Raheem
Keyword(s):  
The Other ◽  
Topological Spaces ◽  
Neutrosophic Sets ◽  
Basic Properties ◽  
Closed Sets ◽  
New Class ◽  
Other Hand ◽  
Definition Of

In this paper, we present and study some of the basic properties of the new class of sets called weakly b-closed sets and weakly b- open sets in fuzzy neutrosophic bi-topological spaces. We referred to some results related to the new definitions, which we taked the case of equal in the definition of b-sets instead of subset. Then, we discussed the relations between the new defined sets by hand and others fuzzy neutrosophic sets which were studied before us on the other hand on fuzzy neutrosophic bi-topological spaces. Then, we have studied some of characteristics and some relations are compared with necessary examples.

scholarly journals Tilings in topological spaces

1999 ◽  
Vol 22 (3) ◽  
pp. 611-616 ◽  
Author(s):  
F. G. Arenas
Keyword(s):  
Topological Space ◽  
Pairwise Disjoint ◽  
The Other ◽  
Vector Spaces ◽  
Topological Spaces ◽  
Topological Vector Spaces ◽  
Other Hand ◽  
Extensive Bibliography

Atilingof a topological spaceXis a covering ofXby sets (calledtiles) which are the closures of their pairwise-disjoint interiors. Tilings ofℝ2have received considerable attention (see [2] for a wealth of interesting examples and results as well as an extensive bibliography). On the other hand, the study of tilings of general topological spaces is just beginning (see [1, 3, 4, 6]). We give some generalizations for topological spaces of some results known for certain classes of tilings of topological vector spaces.

scholarly journals On (fuzzy) pseudo-semi-normed linear spaces

2021 ◽  
Vol 7 (1) ◽  
pp. 467-477
Author(s):  
Yaoqiang Wu ◽  
Keyword(s):  
The Other ◽  
Topological Spaces ◽  
Normed Spaces ◽  
Linear Spaces ◽  
Normed Linear Spaces ◽  
Other Hand ◽  
Fuzzy Topological Spaces

<abstract><p>In this paper, we introduce the notion of pseudo-semi-normed linear spaces, following the concept of pseudo-norm which was presented by Schaefer and Wolff, and illustrate their relationship. On the other hand, we introduce the concept of fuzzy pseudo-semi-norm, which is weaker than the notion of fuzzy pseudo-norm initiated by N$ \tilde{\rm{a}} $d$ \tilde{\rm{a}} $ban. Moreover, we give some examples which are according to the commonly used $ t $-norms. Finally, we establish norm structures of fuzzy pseudo-semi-normed spaces and provide (fuzzy) topological spaces induced by (fuzzy) pseudo-semi-norms, and prove that the (fuzzy) topological spaces are (fuzzy) Hausdorff.</p></abstract>

p-semisimple modules and type submodules

2019 ◽  
Vol 19 (04) ◽  
pp. 2050078
Author(s):  
A. Mozaffarikhah ◽  
E. Momtahan ◽  
A. R. Olfati ◽  
S. Safaeeyan
Keyword(s):  
Abelian Groups ◽  
Large Family ◽  
The Other ◽  
Topological Spaces ◽  
Algebraic Structures ◽  
Semisimple Modules ◽  
Other Hand ◽  
One To One ◽  
Regular Closed

In this paper, we introduce the concept of [Formula: see text]-semisimple modules. We prove that a multiplication reduced module is [Formula: see text]-semisimple if and only if it is a Baer module. We show that a large family of abelian groups are [Formula: see text]-semisimple. Furthermore, we give a topological characterizations of type submodules (ideals) of multiplication reduced modules ([Formula: see text]-semisimple rings). Moreover, we observe that there is a one-to-one correspondence between type ideals of some algebraic structures on one hand and regular closed subsets of some related topological spaces on the other hand. This also characterizes the form of closed ideals in [Formula: see text].

scholarly journals The smallest proper congruence on S(X)

1988 ◽  
Vol 30 (3) ◽  
pp. 301-313 ◽  
Author(s):  
K. H. Hofmann ◽  
K. D. Magill
Keyword(s):  
Topological Space ◽  
Complete Lattice ◽  
The Other ◽  
Topological Spaces ◽  
Other Hand ◽  
Dual Atom ◽  
Lattice Of Congruences

S(X) is the semigroup of all continuous self maps of the topological space X and for any semigroup S, Cong(S) will denote the complete lattice of congruences on S. Cong(S) has a zero Z and a unit U. Specifically, Z = {(a, a):a ∈ S} and U = S × S. Evidently, Z and U are distinct if S has at least two elements. By a proper congruence on S we mean any congruence which differs from each of these. Since S(X) has more than one element when X is nondegenerate, we will assume without further mention that the spaces we discuss in this paper have more than one point. We observed in [4] that there are a number of topological spaces X such that S(X) has a largest proper congruence, that is, Cong(S(X)) has a unique dual atom which is greater than every other proper congruence on S(X). On the other hand, we also found out in [5] that it is also common for S(X) to fail to have a largest proper congruence. We will see that the situation is quite different at the other end of the spectrum in that it is rather rare for S(X) not to have a smallest proper congruence. In other words, for most spaces X, Cong(S(X)) has a unique atom which is smaller than every other proper congruence.

scholarly journals Mutually Compactificable Topological Spaces

2007 ◽  
Vol 2007 ◽  
pp. 1-10
Author(s):  
Martin Maria Kovár
Keyword(s):  
Continuous Function ◽  
Topological Space ◽  
Discrete Space ◽  
The Other ◽  
Regular Space ◽  
Topological Spaces ◽  
Other Hand

Two disjoint topological spacesX,Yare(T2-)mutually compactificable if there exists a compact(T2-)topology onK=X∪Ywhich coincides onX,Ywith their original topologies such that the pointsx∈X,y∈Yhave open disjoint neighborhoods inK. This paper, the first one from a series, contains some initial investigations of the notion. Some key properties are the following: a topological space is mutually compactificable with some space if and only if it isθ-regular. A regular space on which every real-valued continuous function is constant is mutually compactificable with noS2-space. On the other hand, there exists a regular non-T3.5space which is mutually compactificable with the infinite countable discrete space.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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