Some examples of nontrivial homotopy groups of modules

The concept of the homotopy theory of modules was discovered by Peter Hilton as a result of his trip in 1955 to Warsaw, Poland, to work with Karol Borsuk, and to Zurich, Switzerland, to work with Beno Eckmann. The idea was to produce an analog of homotopy theory in topology. Yet, unlike homotopy the...

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Main Author: C. Joanna Su
Format: Article
Language:English
Published: Wiley 2001-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/S0161171201005373
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author C. Joanna Su
author_facet C. Joanna Su
author_sort C. Joanna Su
collection DOAJ
description The concept of the homotopy theory of modules was discovered by Peter Hilton as a result of his trip in 1955 to Warsaw, Poland, to work with Karol Borsuk, and to Zurich, Switzerland, to work with Beno Eckmann. The idea was to produce an analog of homotopy theory in topology. Yet, unlike homotopy theory in topology, there are two homotopy theories of modules, the injective theory, π¯n(A,B), and the projective theory, π¯n(A,B). They are dual, but not isomorphic. In this paper, we deliver and carry out the precise calculation of the first known nontrivial examples of absolute homotopy groups of modules, namely, π¯n(ℚ/ℤ,ℚ/ℤ),  π¯n(ℤ,ℚ/ℤ), and π¯n(ℤ,ℤ), where ℚ/ℤ and ℤ are regarded as ℤCk-modules with trivial action. One interesting phenomenon of the results is the periodicity of these homotopy groups, just as for the Ext groups.
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spelling doaj-art-da07d0423a5e4fbf93de3e7f6cb450052025-02-03T01:02:19ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04252001-01-0127318919510.1155/S0161171201005373Some examples of nontrivial homotopy groups of modulesC. Joanna Su0Department of Mathematical Sciences, State University of New York at Binghamton, Binghamton 13902-6000, NY, USAThe concept of the homotopy theory of modules was discovered by Peter Hilton as a result of his trip in 1955 to Warsaw, Poland, to work with Karol Borsuk, and to Zurich, Switzerland, to work with Beno Eckmann. The idea was to produce an analog of homotopy theory in topology. Yet, unlike homotopy theory in topology, there are two homotopy theories of modules, the injective theory, π¯n(A,B), and the projective theory, π¯n(A,B). They are dual, but not isomorphic. In this paper, we deliver and carry out the precise calculation of the first known nontrivial examples of absolute homotopy groups of modules, namely, π¯n(ℚ/ℤ,ℚ/ℤ),  π¯n(ℤ,ℚ/ℤ), and π¯n(ℤ,ℤ), where ℚ/ℤ and ℤ are regarded as ℤCk-modules with trivial action. One interesting phenomenon of the results is the periodicity of these homotopy groups, just as for the Ext groups.http://dx.doi.org/10.1155/S0161171201005373
spellingShingle C. Joanna Su
Some examples of nontrivial homotopy groups of modules
International Journal of Mathematics and Mathematical Sciences
title Some examples of nontrivial homotopy groups of modules
title_full Some examples of nontrivial homotopy groups of modules
title_fullStr Some examples of nontrivial homotopy groups of modules
title_full_unstemmed Some examples of nontrivial homotopy groups of modules
title_short Some examples of nontrivial homotopy groups of modules
title_sort some examples of nontrivial homotopy groups of modules
url http://dx.doi.org/10.1155/S0161171201005373
work_keys_str_mv AT cjoannasu someexamplesofnontrivialhomotopygroupsofmodules