| 0 = # S0, 0 = n - n0, INVR(S0, S, S1, n0, n, source, dest), INV(S0, S, S1, n0, source), done0 → dest ∈ S0, S0 = ∅ → S = ∅ ⊦ ⟪while S0 ≠ ∅ ∧ ¬ done0 do { choose v with v ∈ S0 in if v = dest then done0 := true else { S0 := S0 -- v ; ADD(succ(v); S1, S) } ; if S0 = ∅ then S0 := S, S := ∅, n0 := n0 + 1 }⟫ ⟪norfail0 := (done0 ⊃ some(n0); fail)⟫ norfail0 = some(n) |
S0 = ∅, S = ∅, ¬ done0, 0 = n - n0, INV(∅, ∅, S1, n0, source), INVR(∅, ∅, S1, n0, n, source, dest) ⊦ ⟪while S0 ≠ ∅ ∧ ¬ done0 do { choose v with v ∈ S0 in if v = dest then done0 := true else { S0 := S0 -- v ; ADD(succ(v); S1, S) } ; if S0 = ∅ then S0 := S, S := ∅, n0 := n0 + 1 }⟫ ⟪norfail0 := (done0 ⊃ some(n0); fail)⟫ norfail0 = some(n)
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ ¬ a ∈ ∅], [CSIMPSEQ : ⊦ # ∅ = 0], [CSIMPFORWARD : ⊦ s ≠ ∅ → # s ≠ 0], [CSIMPFORWARD : ⊦ a ∈ s → s ≠ ∅], [CSIMPFORWARD : ⊦ # s = 0 → s = ∅])]]