It's a relation between two values
@Miaourt I've never seen that relation before, but what that equation is telling you is that ⊥ is an identity element with respect to that relation
like, 0 is an identity with + because x + 0 = 0 + x = x
and 1 is an identity with × because x × 1 = 1 × x = x
It's pronounced ʁaʁyʁe.
And written RaRuRe, or R3 for short.
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