TY - BOOK
DB - /z-wcorg/
DP - http://worldcat.org
ID - 227469361
LA - English
T1 - New proofs of old theorems in logic and formal linguistics.
AU - Floyd, Robert W.
AU - CARNEGIE INST OF TECH PITTSBURGH PA.
PB - Defense Technical Information Center
CY - Ft. Belvoir
Y1 - 1966///
AB - 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).
ER -