Strong soundness of a deductive system is the property that any sentence "P" of the language upon which the deductive system is based that is derivable from a set Γ of sentences of that language is also a logical consequence of that set, in the sense that any model that makes all members of Γ true will also make "P" true. In symbols where Γ is a set of sentences of "L": if Γ ⊢"S" "P", then also Γ ⊨"L" "P". Notice that in the statement of strong soundness, when Γ is empty, we have the statement of weak soundness.