English
ringExpChar R equals q whenever ExpChar R q holds.
Русский
ringExpChar R равно q тогда, когда ExpChar R q выполняется.
LaTeX
$$$\\\\forall R [ ExpChar R q ] \\\\Rightarrow \\\\mathrm{ringExpChar}(R) = q$$$
Lean4
theorem eq (q : ℕ) [h : ExpChar R q] : ringExpChar R = q :=
by
rcases h with _ | h
· haveI := CharP.ofCharZero R
rw [ringExpChar, ringChar.eq R 0]; rfl
rw [ringExpChar, ringChar.eq R q]
exact Nat.max_eq_left h.one_lt.le