In logic, statements <var>p</var> and <var>q</var> are logically equivalent if they have the same logical content. This is a semantic concept; two statements are equivalent if they have the same truth value in every model (Mendelson 1979:56). The logical equivalence of <var>p</var> and <var>q</var> is sometimes expressed as , Epq, or . However, these symbols are also used for material equivalence; the proper interpretation depends on the context. Logical equivalence is different from material equivalence, although the two concepts are closely related.