Where does this come from, and can I check it?

Stephen Kleene described them in 1951 to model simple automata, long before they reached text editors. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

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Yes. It sits on the Technology shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Regular expressions began as a mathematical notation

Stephen Kleene described them in 1951 to model simple automata, long before they reached text editors Kleene's regular sets described the patterns that finite automata can recognise, using union, concatenation and repetition. The notation was picked up in the 1960s for searching text in Unix tools such as grep and sed. Almost every programming language now includes some dialect of it, and the dialects differ just enough to cause bugs. It sits in Mondo's technology collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Britannica

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Tags: programming, mathematics, text-processing

Regular expressions began as a mathematical notation: the short answers

Where does this come from, and can I check it?: Stephen Kleene described them in 1951 to model simple automata, long before they reached text editors. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a technology fact?: Yes. It sits on the Technology shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.