Abstract: Embodiments are directed to indexing and querying a sequence of hash values in an indexing matrix. A computer system accesses a document to extract a portion of text from the document. The computer system applies a hashing algorithm to the extracted text. The hash values of the extracted text form a representative sequence of hash values. The computer system inserts each hash value of the sequence of hash values into an indexing matrix, which is configured to store multiple different hash value sequences. The computer system also queries the indexing matrix to determine how similar the plurality of hash value sequences are to the selected hash value sequence based on how many hash values of the selected hash value sequence overlap with the hash values of the plurality of stored hash value sequences.

Abstract: The present invention extends to methods, systems, and computer program products for decomposing and merging regular expressions. Embodiments of the invention decompose a regular expression into multiple simple keyword graphs, merge those keyword graphs in a compact and efficient manner, and produce a directed acyclic graph (DAG) that can execute a simplified regular expression alphabet. Several of these regular expression DAG's can then be merged together to produce a single DAG that represents an entire collection of regular expressions. DAGs along with other text processing algorithms and a heap collection can be combined in a multi-pass approach to expand the regular expression alphabet.

Abstract: Embodiments are directed to indexing and querying a sequence of hash values in an indexing matrix. A computer system accesses a document to extract a portion of text from the document. The computer system applies a hashing algorithm to the extracted text. The hash values of the extracted text form a representative sequence of hash values. The computer system inserts each hash value of the sequence of hash values into an indexing matrix, which is configured to store multiple different hash value sequences. The computer system also queries the indexing matrix to determine how similar the plurality of hash value sequences are to the selected hash value sequence based on how many hash values of the selected hash value sequence overlap with the hash values of the plurality of stored hash value sequences.