Complex sentence: In linguistics, phrase structure grammars are also known as constituency grammars, which are all those grammars that are based on the constituency relation, as opposed to the dependency relation associated with dependency grammars.
Split into simpler sentences: In linguistics, phrase structure grammars are also known as constituency grammars. Constituency grammars are thus all those grammars that are based on the constituency relation, as opposed to the dependency relation associated with dependency grammars.