Formulas
- Automorphism group
- Automorphisms of the symmetric and alternating groups
- Autonomous convergence theorem
- Autonomous system (mathematics)
- Auxiliary function
- Average crossing number
- Avraham Trahtman
- Axiality and rhombicity
- Axiom
- Axiom A
- Axiom of choice
- Axiom of dependent choice
- Axiom of extensionality
- Axiom of finite choice
- Axiom of infinity