|Equivalence: Relation between sentences. It exists if both sides have the same truth value, so that they are both true or both false.|
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Def equivalence / localization / logical space / Stalnaker: to say that i is equivalent to j, is to say that the localization functions represent i and j in the same world. - Def intrinsic property: Region in logical space that is invariant with respect to this equivalence relation - contrast: conventional property - (see diagram I 83).
Ways a World may be Oxford New York 2003