Abstract: A method and apparatus for searching data to locate a portion identified by a search query. The data may comprise text files in a database. The search query comprises a sequence of two or more data fragments expected to be contained in the portion of data being sought. The method comprises receiving the data fragments and searching the data to locate the first fragment, then searching to find the location of the last. The method may include locating the earliest match between the data and the last data fragment which is preceded by matches between the data and each other fragment, the object being to find the shortest section of data which contains all the fragments in the right sequence and without overlapping one with another. The identified portion of text can be highlighted in a display of the data.

Abstract: A method and apparatus is described for the checking of the correctness and consistency of units and dimensions of variables and constants used in expressions, such as those used in computer programs. The present invention relates to a method (200) and apparatus (100) for performing such checking. A set of user-supplied precompiler directives is added to the computer program that is to be checked. Broadly, functions, function parameters, constants and variables are replaced with strings from the precompiler directives. The resulting expressions are reduced into a standard form. The expressions in the reduced form are tested for homogeneity according to a set of predetermined conditions.

Abstract: In a compiler or program proving or verification software code, it is often useful to analyse a computer program and one way in which this might be partially achieved is by comparing algebraic expressions to see if they are equivalent, i.e. to see if they are derivable from a common template or function definition. Herein a string matching and replacement algorithm is used to compare two functions. Initially, each expression is converted to a “reduced” form by reference to a set of standard rules so as, for example, to ensure that terms comprising the same variables are combined. The variables names in each term are then replaced with symbols to produce, for each expression, a corresponding character string which, arranged in a predetermined order, are compared to determine equivalence of the expressions. To achieve this, a matrix M is formed with entries corresponding to the symbols and the matrix elements are incremented according to pre-set rules.

Abstract: The present invention discloses a method for determining, in a computer environment, the equivalence, if any, of two blocks of assignment statements in a computer program for use in compiler optimization of source code, program verification, program proving, and like computing tasks. The method, inter alia, successfully eliminates, from a block of assignment statements, all intermediate variables and statements which are identities and also those which are irrelevant to the computation of the output variables and brings the block to a form suitable for comparing two or more blocks of assignment statements. A system for carrying out the above method and a computer program product incorporating the method are also disclosed.

Abstract: A method and apparatus for searching data to locate a portion identified by a search query. The data may comprise text files in a database. The search query comprises two or more data fragments expected to be contained in the portion of data being sought and in any order. The method comprises receiving the data fragments and searching the data to locate matches between the data and the respective data fragments. Any overlapping matches are discriminated and replaced by an iterative search process until there is found a minimal portion of the data containing all of the data fragments without overlaps, the term minimal meaning a portion with only one complete set of the data fragments (though some but not all can be duplicated). The identified portion of text can be highlighted in a display of the data.

Abstract: The present invention relates generally to transformation of algebraic expressions into a standard form, and in particular, to the equivalence of original and transformed expressions. The present invention relates to a method and apparatus for performing such transformation, and also to a computer program product including a computer readable medium having recorded thereon a computer program for performing such transformation.

Abstract: The present invention is a method (100) of determining the syntactic correctness of an expression for use in a computing environment. After creating (30) a string of characters from said expression, it looks for substrings (character sequences), which are legitimate and replaces (54) them with a shorter but semantically equivalent substring. It also looks for character sequences which are illegitimate, and replaces (54) them with a substring (i.e. “?”) to indicate that it has met with an illegal sequence. It does these operations repeatedly, and in predetermined sequences, till no further changes in the string can be made; that is, the string achieves a constant length. An expression is determined to be syntactically correct only if said string reduces to a single predetermined character.