Bockstein homomorphism: Difference between revisions
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This is important as a source of [[cohomology operation]]s (see [[Steenrod algebra]]). For coefficients in a [[finite cyclic group]] of order ''n'' as ''R'', the mapping β can be combined with reduction modulo ''n''; and then iterated. |
This is important as a source of [[cohomology operation]]s (see [[Steenrod algebra]]). For coefficients in a [[finite cyclic group]] of order ''n'' as ''R'', the mapping β can be combined with reduction modulo ''n''; and then iterated. |
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==History== |
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The name is for the [[Soviet Union|Soviet]] [[topologist]] from [[Moscow]], [[Meer Feliksovich Bokshtein]] (Bokstein), with Bockstein being a [[French language|French]] transliteration. Little known in the West, he was born October 4, 1913, and died May 2, 1990. |
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==References== |
==References== |
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Revision as of 15:44, 28 March 2011
In mathematics, the Bockstein homomorphism in homological algebra is a connecting homomorphism associated with a short exact sequence
- 0 → P → Q → R → 0
of abelian groups, when they are introduced as coefficients into a chain complex C, and which appears in the homology groups as a homomorphism reducing degree by one,
- β: Hi(C, R) → Hi − 1(C, P).
To be more precise, C should be a complex of free, or at least torsion-free, abelian groups, and the homology is of the complexes formed by tensor product with C (some flat module condition should enter). The construction of β is by the usual argument (snake lemma).
A similar construction applies to cohomology groups, this time increasing degree by one. Thus we have
- β: Hi(C, R) → Hi + 1(C, P).
This is important as a source of cohomology operations (see Steenrod algebra). For coefficients in a finite cyclic group of order n as R, the mapping β can be combined with reduction modulo n; and then iterated.
References
- Bockstein, Meyer (1958), "Sur la formule des coefficients universels pour les groupes d'homologie", Comptes Rendus de l'académie des Sciences. Série I. Mathématique, 247: 396–398, MR0103918
- Hatcher, Allen (2002), Algebraic Topology, Cambridge University Press, ISBN 978-0-521-79540-1, MR1867354.
- Spanier, Edwin H. (1981), Algebraic topology. Corrected reprint, New York-Berlin: Springer-Verlag, pp. xvi+528, ISBN 0-387-90646-0, MR0666554