(?=foo) Lookahead Asserts that what immediately follows the current position in the string is foo
(?<=foo) Lookbehind Asserts that what immediately precedes the current position in the string is foo
(?!foo) Negative Lookahead Asserts that what immediately follows the current position in the string is not foo
(?<!foo) Negative Lookbehind Asserts that what immediately precedes the current position in the string is not foo
L. Kwuida, A. Tepavcevic, и B. Seselja. Proceedings of the 12th International Conference on Conceptual Structures (ICCS 2004), том 3127 из Lecture Notes in Computer Science, стр. 227-241. Springer, (2004)
J. Klinger. Proceedings of the 13th International Conference on Conceptual Structures (ICCS 2005), том 3596 из Lecture Notes in Computer Science, стр. 209-222. Springer, (2005)
M. Leclère, и M. Mugnier. Proceedings of the 14th International Conference on Conceptual Structures (ICCS 2006), том 4068 из Lecture Notes in Computer Science, стр. 331-345. Springer, (2006)