In computer science, the Apostolico–Giancarlo algorithm is a variant of the Boyer–Moore string-search algorithm, the basic application of which is searching for occurrences of a pattern P in a text T. As with other comparison-based string searches, this is done by aligning P to a certain index of T and checking whether a match occurs at that index. P is then shifted relative to T according to the rules of the Boyer–Moore algorithm, and the process repeats until the end of T has been reached. Application of the Boyer–Moore shift rules often results in large chunks of the text being skipped entirely.