English
Given an abstract cancellation hypothesis for u and w, it is impossible that Cancels u w holds; i.e., under this hypothesis, the cancellation predicate is false.
Русский
Для данного гипотезы отмены для u и w невозможно выполняться Cancels u w; то есть при данной гипотезе предикат отмены ложен.
LaTeX
$$$\\lnot \\mathrm{Cancels}(u,w).$$$
Lean4
/-- Multiplying `t^u` by `w` in the special case where cancellation happens -/
def unitsSMulWithCancel (u : ℤˣ) (w : NormalWord d) : Cancels u w → NormalWord d :=
consRecOn w (by simp [Cancels, ofGroup]; tauto) (fun g _ w _ _ _ can => (toSubgroupEquiv φ u ⟨g, can.1⟩ : G) • w)