NOV 1966
(Linguistics
Linguistics
2016-07-10
Floyd
Robert W.
Robert W. Floyd
CARNEGIE INST OF TECH PITTSBURGH PA.
New proofs of old theorems in logic and formal linguistics.
NOV 1966
en
1966
Theorem 1 constructs, from any word problem in a semi-Thue system, an equivalent Post correspondence problem, showing the undecidability of the general Post correspondence problem. Theorem 2 constructs, from any Post correspondence problem, a minimal linear grammar which is ambiguous exactly if the Post correspondence problem has a solution, showing the undecidability of the general ambiguity problem. (Other standard undecidability results on phrase structure grammars are implied.) Theorem 3 constructs, from any word problem in a semi-Thue system, an ambiguity problem, combining the results of Theorem 1 and 2 by more direct means. No new results are presented, but standard proofs were shortened and constructions eliminated, combined, or simplified. (Author).
227469361
227469361
vau
Grammars
Defense Technical Information Center
Ft. Belvoir
Theorems)