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Classes associées à un $$\pi$$-module différentiel. (French) Zbl 0532.55023
For each graded G-module $$C_*$$ (G a discrete group) an element in $$Ext^ 2_ G(H_ q(C_*),H_{q+1}(C_*))$$ is defined, which leads to an explicit description of the differential $$d_ 2$$ in certain spectral sequences.
Reviewer: H.Hösli

##### MSC:
 55T10 Serre spectral sequences 18G15 Ext and Tor, generalizations, Künneth formula (category-theoretic aspects) 55R20 Spectral sequences and homology of fiber spaces in algebraic topology