Weak commutativity, virtually nilpotent groups, and Dehn functions

The group <i>X</i>(<i>G</i>) is obtained from <i>G</i>∗<i>G</i> by forcing each element <i>g</i> in the first free factor to commute with the copy of <i>g</i> in the second free factor. We make significant additions to the list...

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मुख्य लेखकों: Bridson, MR, Kochloukova, DH
स्वरूप: Journal article
भाषा:English
प्रकाशित: EMS Press 2023
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author Bridson, MR
Kochloukova, DH
author_facet Bridson, MR
Kochloukova, DH
author_sort Bridson, MR
collection OXFORD
description The group <i>X</i>(<i>G</i>) is obtained from <i>G</i>∗<i>G</i> by forcing each element <i>g</i> in the first free factor to commute with the copy of <i>g</i> in the second free factor. We make significant additions to the list of properties that the functor <i>X</i> is known to preserve. We also investigate the geometry and complexity of the word problem for <i>X</i>(<i>G</i>). Subtle features of <i>X</i>(<i>G</i>) are encoded in a normal abelian subgroup <i>W</i><<i>X</i>(<i>G</i>) that is a module over <i>ZQ</i>, where <i>Q</i>=<i>H</i><sub>1</sub>​ (<i>G</i>,<i>Z</i>). We establish a structural result for this module and illustrate its utility by proving that <i>X</i> preserves virtual nilpotence, the Engel condition, and growth type – polynomial, exponential, or intermediate. We also use it to establish isoperimetric inequalities for <i>X</i>(<i>G</i>) when <i>G</i> lies in a class that includes Thompson's group <i>F</i> and all non-fibred Kähler groups. The word problem is soluble in <i>X</i>(<i>G</i>) if and only if it is soluble in <i>G</i>. The Dehn function of <i>X</i>(<i>G</i>) is bounded below by a cubic polynomial if <i>G</i> maps onto a non-abelian free group.
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spelling oxford-uuid:3a4d8db1-793d-494c-a3d6-140634bc32cf2024-05-22T16:43:25ZWeak commutativity, virtually nilpotent groups, and Dehn functionsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:3a4d8db1-793d-494c-a3d6-140634bc32cfEnglishSymplectic ElementsEMS Press2023Bridson, MRKochloukova, DHThe group <i>X</i>(<i>G</i>) is obtained from <i>G</i>∗<i>G</i> by forcing each element <i>g</i> in the first free factor to commute with the copy of <i>g</i> in the second free factor. We make significant additions to the list of properties that the functor <i>X</i> is known to preserve. We also investigate the geometry and complexity of the word problem for <i>X</i>(<i>G</i>). Subtle features of <i>X</i>(<i>G</i>) are encoded in a normal abelian subgroup <i>W</i><<i>X</i>(<i>G</i>) that is a module over <i>ZQ</i>, where <i>Q</i>=<i>H</i><sub>1</sub>​ (<i>G</i>,<i>Z</i>). We establish a structural result for this module and illustrate its utility by proving that <i>X</i> preserves virtual nilpotence, the Engel condition, and growth type – polynomial, exponential, or intermediate. We also use it to establish isoperimetric inequalities for <i>X</i>(<i>G</i>) when <i>G</i> lies in a class that includes Thompson's group <i>F</i> and all non-fibred Kähler groups. The word problem is soluble in <i>X</i>(<i>G</i>) if and only if it is soluble in <i>G</i>. The Dehn function of <i>X</i>(<i>G</i>) is bounded below by a cubic polynomial if <i>G</i> maps onto a non-abelian free group.
spellingShingle Bridson, MR
Kochloukova, DH
Weak commutativity, virtually nilpotent groups, and Dehn functions
title Weak commutativity, virtually nilpotent groups, and Dehn functions
title_full Weak commutativity, virtually nilpotent groups, and Dehn functions
title_fullStr Weak commutativity, virtually nilpotent groups, and Dehn functions
title_full_unstemmed Weak commutativity, virtually nilpotent groups, and Dehn functions
title_short Weak commutativity, virtually nilpotent groups, and Dehn functions
title_sort weak commutativity virtually nilpotent groups and dehn functions
work_keys_str_mv AT bridsonmr weakcommutativityvirtuallynilpotentgroupsanddehnfunctions
AT kochloukovadh weakcommutativityvirtuallynilpotentgroupsanddehnfunctions