English
A semigroup multiplication satisfies the (non-commutative) Jordan axioms.
Русский
Умножение в полугруппе удовлетворяет некоммутативным аксиомам Джордана.
LaTeX
$$IsJordan A for [Semigroup A]$$
Lean4
/-- Semigroup multiplication satisfies the (non-commutative) Jordan axioms -/
instance (priority := 100) isJordan [Semigroup A] : IsJordan A
where
lmul_comm_rmul a b := by rw [mul_assoc]
lmul_lmul_comm_lmul a b := by rw [mul_assoc, mul_assoc]
lmul_comm_rmul_rmul a b := by rw [mul_assoc]
lmul_lmul_comm_rmul a b := by rw [← mul_assoc]
rmul_comm_rmul_rmul a
b := by
rw [← mul_assoc, ← mul_assoc]
-- see Note [lower instance priority]