Grammar defines the geometric and combinatorial constraints of sentence construction. A Prolog parser functions like a domino playing machine. Prolog backtracking is equivalent to removing dominos from the board. Parallel Prolog parsing strategies. The domino playing parser is matching a string with a phrase marker.
Linguistic research defines the possible complexity of puzzle pieces.
Phrase markers defined by g08110 and g0811. Selection Restrictions Figure 8.25. A phrase marker with some complement and adjunct constructions labeled.