Prove that the subtraction operation for ordinal numbers coincides with the following operation defined by recursion:
α -* α=0
β+ -* α=(β-* α)+ for α ≤ β
γ-* α=sup{β-* α:β < γ} when γ is alimit.
Prove that the subtraction operation for ordinal numbers coincides with the following operation defined by recursion:
α -* α=0
β+ -* α=(β-* α)+ for α ≤ β
γ-* α=sup{β-* α:β < γ} when γ is alimit.