Supported representatives through the connecting map (Corollary 10.5, coefficient form) #
cor:zero-supported-coverage (integral-deformations.tex) on the coefficient complexes
of CharComplex, with ๐ช = โค/4 and the sequence 0 โ ๐ฝโ โ ๐ช โ ๐ฝโ โ 0: Lemma 10.4
(supported_bockstein) applies to Cยน โ Cยฒ โ Cยณ of character ฯ with U the pairs (u, v)
with uv = 0 whose stem product is the ray wโ(u, v). Condition (2) is Theorem 9.1(3): a
derivation modulo two has nonzero-product Leibniz coefficients (IsSol), which lift to โค
by integral_lifting; the lifted coboundary vanishes on nonzero products and lands in the stem
lines at zero products (d1_isSol_mem_U). Condition (1) is Proposition 10.3 (IStar). This
gives the corollary over ๐ฝโ (cor105_coeffโ); "It may be chosen over ๐ฝโ and then extended
to k": a class over k has a coordinate class over ๐ฝโ which is not a coboundary, and a
retraction k โ ๐ฝโ shows that its supported representative stays a non-coboundary over k
(cor105_coeff).
A coboundary is a cocycle.
The complex as linear maps #
The index set of three-cochain coefficients.
Instances For
dโ as a linear map.
Instances For
dโ as a linear map.
Instances For
The coordinates of U: zero products whose stem product is the ray wโ.
Instances For
Solutions of the Leibniz equations #
The lifted coboundary is supported on stem lines #
A nonzero substitution u vโบ at a zero product lies on the stem line.
A nonzero substitution uโบ v at a zero product lies on the stem line.
The coboundary of a solution of the nonzero-product Leibniz equations is supported on the
stem lines of zero products (cor:zero-supported-coverage, proof).
A one-cocycle gives a solution of the nonzero-product Leibniz equations.
Condition (2): lifting derivations to โค/4 #
Solutions with values in ๐ฝโ lift to ๐ช = โค/4: Theorem 9.1(3).
Condition (2) of Lemma 10.4.
Proposition 10.3 in coefficients (prop:integral-bockstein, i_* = 0): twice a
cochain over ๐ช = โค/4 whose reduction is a cocycle is a coboundary.
Instances For
Proposition 10.3, surjectivity of the connecting map (prop:integral-bockstein): every
two-cocycle c over ๐ฝโ of character ฯ is ฮฒ of a derivation: there is a one-cochain ฮด
over ๐ช = โค/4 with dฮด = 2cฬ whose reduction is a cocycle, i.e. c = (dฮด)/2.
Corollary 10.5 over ๐ฝโ (cor:zero-supported-coverage): given Proposition 10.3, a
cocycle of character ฯ which is not a coboundary yields one supported on the stem lines of
zero products which is not a coboundary.
Corollary 10.5 in coefficients (cor:zero-supported-coverage), over k: the
corollary over ๐ฝโ, extended to k.