Supported summands of a bifunctor totalization #
A term of Mathlib's bifunctor totalization is the coproduct of its summands over the fiber of the total index map. When all but one or two summands are zero, the term identifies with the remaining summand or their binary biproduct. The comparisons below use the existing totalization inclusions and desc maps. Their characteristic equations compute the supported inclusions and the inverse maps.
A totalization term with only one potentially nonzero summand is that summand.
Instances For
The unique supported inclusion is the inverse of the single-summand comparison.
The unique supported inclusion is the inverse of the single-summand comparison.
The inverse of the single-summand comparison is the totalization inclusion.
A totalization term with two potentially nonzero summands is their binary biproduct.
Instances For
The first supported inclusion computes as the first biproduct inclusion.
The first supported inclusion computes as the first biproduct inclusion.
The second supported inclusion computes as the second biproduct inclusion.
The second supported inclusion computes as the second biproduct inclusion.
The inverse two-summand comparison is the desc map of the supported inclusions.