Elementary inductive definitions in HA: from strictly positive towards monotone

TY - JOUR

T1 - Elementary inductive definitions in HA

T2 - from strictly positive towards monotone

AU - Roorda, Dirk

PY - 1990

Y1 - 1990

N2 - A study of elementary inductive definitions (e.i.d.) in HA. Strictly positive e.i.d. have closure ordinals ≤ω, and define predicates that are already definable in HA. We enlarge this class by adding so-called J-operators, for example ⌝ ⌝. E.i.d. in this larger class have closure ordinals up to ω+ω, but they are conservative over HA w.r.t. definability.

AB - A study of elementary inductive definitions (e.i.d.) in HA. Strictly positive e.i.d. have closure ordinals ≤ω, and define predicates that are already definable in HA. We enlarge this class by adding so-called J-operators, for example ⌝ ⌝. E.i.d. in this larger class have closure ordinals up to ω+ω, but they are conservative over HA w.r.t. definability.

U2 - 10.1016/0019-3577(90)90037-N

DO - 10.1016/0019-3577(90)90037-N

M3 - Article

SN - 0019-3577

VL - 11

SP - 105

JO - Indagationes Mathematicae

JF - Indagationes Mathematicae

ER -