6.3.4 Existential Instantiation.

• 3x(P(x))
• ——–
• P(a) ; a must not have been used before

Existential Instantiation claims that if there exists an object for which property ‘P’ is true, then it can be claimed that some unused object has this property. In this case, ‘a’ becomes a placeholder for the object. Variables

Existential Instantiation uses exactly one reference.