Permutational Grammar, PG, is a grammar inspired by the Free Word Order grammar, FOG, presented in Vladimir Pericliev & Alexander Grigorov 1992. Some languages, notably Latin, are said to have free word order, see e.g. Siewierska 1988. The name Permutational Grammar is derived from the use of permutations in order to generate order variation. The general problem to be solved by FOG and PG is the generation and analysis of a great number of word order variants with (roughly) the same meaning. PG accomplishes this by specifying some basic phrase structure orders with their functional (and semantic) representations, and then permuting the corresponding sequences of constituents to obtain all the other sequences with the same meaning. Permutational Grammar can be regarded as a generative phrase structure grammar with transformations represented by permutations. It is developed from SWETRA grammar (see Sigurd 1994). The constituent parsing trees are not represented explicitly. PG is written with generative rewrite rules and implemented in Prolog via the Definite Clause Grammar (DCG) formalism. The Prolog implementation used here is LPAProlog. The rules state that permutations of the constituents to the right of the rewrite symbol have the functional representation given as an argument to the left of the rewrite symbol. These rewrite rules can be compiled into rules that generate all possible permutations of the basic word order ‘on the fly’. It is possible to apply constraints to the permutations generated. One may, for example, introduce an order constraint like imbefore(C1,C2,M), which states that a constituent matching the description C1 must occur immediately before another constituent matching C2 in the list of constituents M. Another example is last(C,M), which states that a C must occur last in the list
