 A close relative of algebraic theories is the object theory of Zalta (1988). It also supplies distinct fine-grained meanings to, e.g., be the suitably distinct inputs so that “John believes all triangles have internal angles that add up to 180°” and “John believes all trilaterals have internal angles that add up to 180°” express different propositions. Zalta says a little more about the identity conditions of his hyperintensionally-distinguished properties: according to Zalta, properties are identical if and only if they are encoded by the same objects.