Weakly additive cohomology

Autores: E. Spanier
Localización: Publicacions matematiques, ISSN 0214-1493, Vol. 34, Nº 1, 1990, págs. 145-150
Idioma: inglés
DOI: 10.5565/publmat_34190_11
Títulos paralelos:
- Cohomología debilmente aditiva
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Resumen
- In this paper the concept of weakly additive cohomology theory is introduced as a variant of the known concept of additive cohomology theory. It is shown that for a closed A in X the singular homology of the pair (X, X-A) (with some fixed cohomology group) regarded as a furcter of A is a weakly additive cohomology theory on any collectionwise normal space X. Furthermore, every compactly supported cohomology theory is weakly additive.
  
  The main result is a comparison theorem for two cohomology theories on X both of which are additive or both of which are weakly additive which recomposes the previously known comparison theorems.