On the Relative Efficiencies of Context-Free Grammar Recognizers A number of diverse recognition procedures that have been proposed for parsing sentences with respect to a context-free grammar are described in this paper by means of a common device. Each procedure is defined by giving an algorithm for obtaining a nondeterministic Turing Machine recognizer that is equivalent to a given context-free grammar. The formalization of the Turing Machine has been chosen to make possible particularly simple description of the parsing procedures considered. An attempt has been made to compare recognition efficiencies for the procedures defined. For a few simple grammars and sentences a formal comparison has been made. Empirical comparison of the recognition of more realistic programming languages such as LISP and ALGOL has been made by means of a program which simulates the Turing Machine on the Univac M-460 computer. Several algorithms for producing grammars equivalent to a given context-free grammar have been considered, and the increase in recognition efficiency they afford has been empirically investigated. CACM May, 1965 Griffiths, T. V. Petrick, S. R. CA650506 JB March 7, 1978 2:38 PM 1046 4 1265 1062 4 1265 1086 4 1265 1105 4 1265 1121 4 1265 1132 4 1265 1139 4 1265 1139 4 1265 1139 4 1265 1140 4 1265 1151 4 1265 1234 4 1265 1234 4 1265 1263 4 1265 1263 4 1265 1265 4 1265 1265 4 1265 1265 4 1265 1265 4 1265 1265 4 1265 1270 4 1265 1323 4 1265 1358 4 1265 1379 4 1265 1380 4 1265 1453 4 1265 1464 4 1265 1484 4 1265 1491 4 1265 1496 4 1265 1498 4 1265 1613 4 1265 1614 4 1265 1665 4 1265 1781 4 1265 1781 4 1265 1781 4 1265 1824 4 1265 1825 4 1265 1860 4 1265 2083 4 1265 2126 4 1265 2178 4 1265 2179 4 1265 2252 4 1265 2325 4 1265 2341 4 1265 2546 4 1265 2546 4 1265 464 4 1265 2645 4 1265 2652 4 1265 2684 4 1265 2769 4 1265 2842 4 1265 2929 4 1265 2934 4 1265 584 4 1265 3069 4 1265 631 4 1265 653 4 1265 669 4 1265 679 4 1265 680 4 1265 691 4 1265 720 4 1265 759 4 1265 761 4 1265 763 4 1265 763 4 1265 795 4 1265 799 4 1265 945 4 1265 949 4 1265 989 4 1265 1265 5 1265 1265 5 1265 1265 5 1265 1350 5 1265 1399 5 1265 1659 5 1265 1768 5 1265 1781 5 1265 1945 5 1265 2110 5 1265 404 5 1265 464 5 1265 3094 5 1265 3184 5 1265 631 5 1265 635 5 1265 823 6 1265 123 6 1265 196 6 1265 914 6 1265 915 6 1265 917 6 1265 919 6 1265 984 6 1265 989 6 1265 990 6 1265 990 6 1265 1007 6 1265 1012 6 1265 1012 6 1265 1046 6 1265 1084 6 1265 1098 6 1265 1122 6 1265 1131 6 1265 1138 6 1265 1139 6 1265 1139 6 1265 1140 6 1265 1141 6 1265 1141 6 1265 1149 6 1265 1198 6 1265 1200 6 1265 1215 6 1265 1223 6 1265 1223 6 1265 1225 6 1265 1225 6 1265 1265 6 1265 1265 6 1265 1265 6 1265 1265 6 1265 1265 6 1265 1265 6 1265 1265 6 1265 1265 6 1265 1303 6 1265 1323 6 1265 1336 6 1265 1350 6 1265 1358 6 1265 1366 6 1265 1396 6 1265 1399 6 1265 1421 6 1265 1455 6 1265 1460 6 1265 1462 6 1265 1463 6 1265 1467 6 1265 1468 6 1265 1477 6 1265 1477 6 1265 1487 6 1265 1491 6 1265 1491 6 1265 1496 6 1265 1496 6 1265 1531 6 1265 1535 6 1265 1565 6 1265 1601 6 1265 1602 6 1265 1613 6 1265 1614 6 1265 1626 6 1265 1641 6 1265 1671 6 1265 1697 6 1265 1781 6 1265 1781 6 1265 1787 6 1265 1788 6 1265 205 6 1265 224 6 1265 249 6 1265 288 6 1265 316 6 1265 381 6 1265 398 6 1265 11 6 1265 2179 6 1265 2645 6 1265 404 6 1265 410 6 1265 463 6 1265 464 6 1265 483 6 1265 483 6 1265 3184 6 1265 3188 6 1265 584 6 1265 584 6 1265 600 6 1265 669 6 1265 680 6 1265 680 6 1265 680 6 1265 691 6 1265 763 6 1265 763 6 1265 799 6 1265