Introducing the pushdown operator: a proposal to extend regular expressions to context-free languages
Alexandre Tadeu Rossini da Silva, Guilherme da Cruz Oliveira, Tanilson Dias dos Santos · 2025
This research proposes a new operator, called the pushdown operator, to be used in combination with the classical operators of regular expressions and aims to increase the denotational power of regular expressions in order to express the set of context-free languages. A literature review was conducted covering the main concepts related to formal languages and denotational formalisms, with an emphasis on context-free languages, which serve as a theoretical basis to support this research. Finally, the formal definition of the pushdown operator is presented, along with comparisons to the other two denotational formalisms of context-free languages found in the literature.