Computability of Generalized Graphs

We investigate conditions under which a semicomputable set is computable. In particular, we study topological pairs <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(<...

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Main Authors: Zvonko Iljazović, Matea Jelić
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Mathematics
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Online Access:https://www.mdpi.com/2227-7390/12/22/3468
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author Zvonko Iljazović
Matea Jelić
author_facet Zvonko Iljazović
Matea Jelić
author_sort Zvonko Iljazović
collection DOAJ
description We investigate conditions under which a semicomputable set is computable. In particular, we study topological pairs <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> which have a computable type, which means that in any computable topological space, a semicomputable set <i>S</i> is computable if there exists a semicomputable set <i>T</i> such that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>S</mi><mo>,</mo><mi>T</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> is homeomorphic to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula>. It is known that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>G</mi><mo>,</mo><mi>E</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> has a computable type if <i>G</i> is a topological graph and <i>E</i> is the set of all its endpoints. Furthermore, the same holds if <i>G</i> is a so-called chainable graph. We generalize the notion of a chainable graph and prove that the same result holds for a larger class of spaces.
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spelling doaj-art-7571dfc84426447e81efc6879f103cb72025-08-20T02:04:54ZengMDPI AGMathematics2227-73902024-11-011222346810.3390/math12223468Computability of Generalized GraphsZvonko Iljazović0Matea Jelić1Faculty of Science, University of Zagreb, 10000 Zagreb, CroatiaFaculty of Civil Engineering, Architecture and Geodesy, University of Split, 21000 Split, CroatiaWe investigate conditions under which a semicomputable set is computable. In particular, we study topological pairs <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> which have a computable type, which means that in any computable topological space, a semicomputable set <i>S</i> is computable if there exists a semicomputable set <i>T</i> such that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>S</mi><mo>,</mo><mi>T</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> is homeomorphic to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>A</mi><mo>,</mo><mi>B</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula>. It is known that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo stretchy="false">(</mo><mi>G</mi><mo>,</mo><mi>E</mi><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> has a computable type if <i>G</i> is a topological graph and <i>E</i> is the set of all its endpoints. Furthermore, the same holds if <i>G</i> is a so-called chainable graph. We generalize the notion of a chainable graph and prove that the same result holds for a larger class of spaces.https://www.mdpi.com/2227-7390/12/22/3468computable topological spacecomputable typetopological graphchainable graphgeneralized graph
spellingShingle Zvonko Iljazović
Matea Jelić
Computability of Generalized Graphs
Mathematics
computable topological space
computable type
topological graph
chainable graph
generalized graph
title Computability of Generalized Graphs
title_full Computability of Generalized Graphs
title_fullStr Computability of Generalized Graphs
title_full_unstemmed Computability of Generalized Graphs
title_short Computability of Generalized Graphs
title_sort computability of generalized graphs
topic computable topological space
computable type
topological graph
chainable graph
generalized graph
url https://www.mdpi.com/2227-7390/12/22/3468
work_keys_str_mv AT zvonkoiljazovic computabilityofgeneralizedgraphs
AT mateajelic computabilityofgeneralizedgraphs