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  2. Comparison of parser generators - Wikipedia

    en.wikipedia.org/.../Comparison_of_parser_generators

    A classic example of a problem which a regular grammar cannot handle is the question of whether a given string contains correctly nested parentheses. (This is typically handled by a Chomsky Type 2 grammar, also termed a context-free grammar.)

  3. Regular expression - Wikipedia

    en.wikipedia.org/wiki/Regular_expression

    However, there can be many ways to write a regular expression for the same set of strings: for example, (Hän|Han|Haen)del also specifies the same set of three strings in this example. Most formalisms provide the following operations to construct regular expressions. Boolean "or" A vertical bar separates alternatives.

  4. Deterministic finite automaton - Wikipedia

    en.wikipedia.org/wiki/Deterministic_finite_automaton

    An example of a deterministic finite automaton that accepts only binary numbers that are multiples of 3. The state S 0 is both the start state and an accept state. For example, the string "1001" leads to the state sequence S 0, S 1, S 2, S 1, S 0, and is hence accepted.

  5. Boyer–Moore string-search algorithm - Wikipedia

    en.wikipedia.org/wiki/Boyer–Moore_string-search...

    P denotes the string to be searched for, called the pattern. Its length is m. S[i] denotes the character at index i of string S, counting from 1. S[i..j] denotes the substring of string S starting at index i and ending at j, inclusive. A prefix of S is a substring S[1..i] for some i in range [1, l], where l is the length of S.

  6. Boolean model of information retrieval - Wikipedia

    en.wikipedia.org/wiki/Boolean_model_of...

    The (standard) Boolean model of information retrieval (BIR) [1] is a classical information retrieval (IR) model and, at the same time, the first and most-adopted one. [2] The BIR is based on Boolean logic and classical set theory in that both the documents to be searched and the user's query are conceived as sets of terms (a bag-of-words model ).

  7. Boolean expression - Wikipedia

    en.wikipedia.org/wiki/Boolean_expression

    In computer science, a Boolean expression is an expression used in programming languages that produces a Boolean value when evaluated. A Boolean value is either true or false.A Boolean expression may be composed of a combination of the Boolean constants True/False or Yes/No, Boolean-typed variables, Boolean-valued operators, and Boolean-valued functions.

  8. Search for messages in AOL Mail

    help.aol.com/articles/search-for-messages-in-new...

    Basic search - Enter keywords in the top search bar, then click the Search icon Search by sender - When viewing a list of emails, mouse over 1 and click the Search icon Search with a single criteria

  9. Boyer–Moore–Horspool algorithm - Wikipedia

    en.wikipedia.org/wiki/Boyer–Moore–Horspool...

    It is a simplification of the Boyer–Moore string-search algorithm which is related to the Knuth–Morris–Pratt algorithm. The algorithm trades space for time in order to obtain an average-case complexity of O(n) on random text, although it has O(nm) in the worst case, where the length of the pattern is m and the length of the search string ...