- Bockstein homomorphism
In
mathematics , the Bockstein homomorphism inhomological algebra is aconnecting homomorphism associated with ashort exact sequence :0 → "P" → "Q" → "R" → 0
of
abelian group s, when they are introduced as coefficients into achain complex "C", and which appears in the homology groups as a homomorphism reducing degree by one,:β: "H""i"("C", "R") → "H""i" − 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" (someflat module condition should enter). The construction of β is by the usual argument (snake lemma ).A similar construction applies to
cohomology group s, this time increasing degree by one. Thus we have:β: "H""i"("C", "R") → "H""i" + 1("C", "P").
This is important as a source of
cohomology operation s (seeSteenrod algebra ). For coefficients in afinite cyclic group of order "n" as "R", the mapping β can be combined with reduction modulo "n"; and then iterated.History
The name is for the Soviet
topologist fromMoscow ,Meer Feliksovich Bokshtein (Bokstein), with Bockstein being a French transliteration. Little known in the West, he was bornOctober 4 ,1913 , and diedMay 2 ,1990 .References
* citation
last= Bockstein
first= Meyer
title= Sur la formule des coefficients universels pour les groupes d'homologie
journal=Comptes Rendus de l'académie des Sciences. Série I. Mathématique
volume= 247
year= 1958
pages= 396–398
url=
doi=
id= MR|0103918
* citation
first= Allen
last= Hatcher
author-link= Allen Hatcher
title= Algebraic Topology
url= http://www.math.cornell.edu/%7Ehatcher/AT/ATpage.html
year= 2002
publisher=Cambridge University Press
isbn= 978-0-521-79540-1
id= MR|1867354 .
*citation|id=MR|0666554|last= Spanier|first= Edwin H.|author-link=Edwin Spanier| title= Algebraic topology. Corrected reprint |publisher=Springer-Verlag |publication-place= New York-Berlin|year= 1981|pages= xvi+528| isbn= 0-387-90646-0
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