| ⊦ (⌜x⌝ + σ1)[m] = σ1[m - (# ⌜x⌝ ).n], ⌜m⌝ < # ⌜x⌝ |
# x ≤ m ⊦ (⌜x⌝ + σ1)[m] = σ1[m - # x]
Used simplifier rules: size-fin: ⊦ # ⌜x⌝ = ⌜# x⌝ ;%lels: ⊦ ¬ m < n ↔ n ≤ m; from specification nat%less-fin: ⊦ ⌜m⌝ < ⌜n⌝ ↔ m < n; from specification nat-inf%sel: ⊦ ⌜m⌝ .n = m; from specification nat-inf-basic