Coinitial Grapfis and Whitehead Automorphisms
1979 ◽
Vol 31
(1)
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pp. 112-123
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Keyword(s):
Coinitial graphs were used in [2; 3 ; 4] as a combinatorial tool in the Reidemeister- Schreier process in order to prove subgroup theorems for Fuchsian groups. Whitehead had previously introduced such graphs but used topological methods for his proofs [8; 9]. Subsequently Rapaport [7] and Iliggins and Lyndon [1] gave algebraic proofs of the results in [9], and AIcCool [5; 6] has further developed these methods so that presentations of automorphism groups could be found.In this paper it is shown that Whitehead automorphisms can be described by a “cutting and pasting” operation on coinitial graphs. Section 1 defines and gives some combinatorial properties of these operations, based on [1].
2001 ◽
Vol 64
(2)
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pp. 257-272
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Keyword(s):
2005 ◽
Vol 15
(01)
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pp. 59-72
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2010 ◽
Vol 42
(10)
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pp. 49-59
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Keyword(s):
2020 ◽
Vol 51
(4)
◽
pp. 1919-1930
Keyword(s):