Implicational propositional calculus
In mathematical logic, the implicational propositional calculus is a version of classical propositional calculus that uses only one connective, called implication or conditional. In formulas, this binary operation is indicated by "implies", "if ..., then ...", "→", " → {\displaystyle \rightarrow } ", etc..
Source: Wikipedia — Implicational propositional calculus (CC BY-SA 4.0)