The mod-
Adams spectral sequence is a spectral sequence
built from mod-
cohomology that computes
-completed stable homotopy under its convergence hypotheses.
For the sphere its second page is
where
is the mod-
Steenrod algebra and
is Adams filtration. A permanent cycle determines a class
in the associated graded homotopy group, which
can have several representatives before passage to that quotient. The stem is
, not the internal degree
. The odd-primary
Kervaire invariant problem at the prime three
concerns a particular family in this spectral sequence.