Trace nondegeneracy, in Hom-typed form #
HomSpace.eq_zero_of_traces_vanish is stated at the HomSpace
level; the Karoubi envelope needs it at morphisms of skein objects,
where the closure partner ranges over morphisms rather than
fragments. Both forms are the same statement read through
HomSpace.ofFragment.
With the nilpotent-trace vanishing of BlockFactorialTrace, this is
what isSemisimpleRing_of_trace consumes to make every skein
endomorphism algebra semisimple.
theorem
RS.end_eq_zero_of_traces_vanish
{R : ℕ}
(f : EdgeRankParameter R)
(Y : SkeinObj f)
(a : Y ⟶ Y)
(ha : ∀ (b : Y ⟶ Y), (HomSpace.traceMap f.val Y.arity) (CategoryTheory.CategoryStruct.comp a b) = 0)
:
Trace nondegeneracy in the fully Hom-typed form: an endomorphism of a skein object all of whose composites have vanishing trace is zero.
theorem
RS.hom_eq_zero_of_traces_vanish'
{R : ℕ}
(f : EdgeRankParameter R)
(Y Z : SkeinObj f)
(a : Y ⟶ Z)
(ha : ∀ (b : Z ⟶ Y), (HomSpace.traceMap f.val Y.arity) (CategoryTheory.CategoryStruct.comp a b) = 0)
:
Mixed-Hom trace nondegeneracy: a morphism between skein objects all of whose closures against reverse morphisms have vanishing trace is zero.