PAβ | ππβ» | Finitely axiomatized fragment of PA | |
Iopenβ | πOpen | PAβ + Induction of open formula | |
IΞ£0β | ππΊβ | PAβ + Induction of Ξ£0β formula | Theory IΞ£0β |
IΞ£0β+Ξ©1β | ππΊβ + Ξ©β | IΞ£0β + Ξ©1β-axiom | |
EA | ππ | Elementary arithmetic | |
IΞ£1β | ππΊβ | PAβ + Induction of Ξ£1β formula | Theory IΞ£1β |
PA | ππ | Peano arithmetic | |