| ⊦ ordered<(x + y + z) → ordered<(x + z) |
ordered<(x + y + z), ¬ ordered<(x + z) ⊦
| ordered<(x + y + z), ¬ ordered<(x + z) ⊦ |
⊦ x ≠ [] ∧ y ≠ [] → (ordered<(x + y) ↔ ordered<(x) ∧ ordered<(y) ∧ x.last < y.head)
y + z ≠ [], x ≠ [], x.last < (y + z).head, ordered<(x), ordered<(y + z), ¬ ordered<(x + z) ⊦
Used simplifier rules: ordered-append-second: ⊦ ordered<(x + y) → ordered<(y); ⊦ x + y = [] ↔ x = [] ∧ y = []; (s) ⊦ [] + x = x; (s) ⊦ x + [] = x; (s) a: ⊦ (x + y) + z = x + y + z; from specification list Used terms: x, y + z
| ⊦ x ≠ [] ∧ y ≠ [] → (ordered<(x + y) ↔ ordered<(x) ∧ ordered<(y) ∧ x.last < y.head) |
| y + z ≠ [], x ≠ [], x.last < (y + z).head, ordered<(x), ordered<(y + z), ¬ ordered<(x + z) ⊦ |
x ≠ [], x.last < (y + z).head, ordered<(y + z), ordered<(x), ¬ ordered<(x + z) ⊦ y = [] ∧ z = []
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list ⊦ x + y = [] ↔ x = [] ∧ y = []; (s)
| x ≠ [], x.last < (y + z).head, ordered<(y + z), ordered<(x), ¬ ordered<(x + z) ⊦ y = [] ∧ z = [] |
y + z = a + y0, y + z ≠ [], x ≠ [], x.last < a, ordered<(x), ordered<(y + z), ¬ ordered<(x + z) ⊦ y = [] ∧ z = []
Used simplifier rules: ⊦ x + y = [] ↔ x = [] ∧ y = []; (s) a: ⊦ (x + y) + z = x + y + z; from specification list x ≠ [] ⊦ a = x.head ∧ y = x.tail ↔ x = a + y; (elim) Used terms: y + z, a, y0
| y + z = a + y0, y + z ≠ [], x ≠ [], x.last < a, ordered<(x), ordered<(y + z), ¬ ordered<(x + z) ⊦ y = [] ∧ z = [] |
y + z = a ' + y0, x ≠ [], z ≠ [], x.last < a, z.head < a, ordered<(x), ordered<(y + z), ¬ x.last < z.head, a ∈ y ∨ a ∈ z ⊦
Used simplifier rules: ordered-append: ⊦ x ≠ [] ∧ y ≠ [] → (ordered<(x + y) ↔ ordered<(x) ∧ ordered<(y) ∧ x.last < y.head); ordered-append-second: ⊦ ordered<(x + y) → ordered<(y); nll: ⊦ ¬ b < a ∧ b < c → a < c; (forward) from specification weakord[tord] a: ⊦ (x + y) + z = x + y + z; from specification list in-14: ⊦ a ' + x = y → a ∈ y; (forward) from specification list ⊦ x + [] = x; (s) ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s) ⊦ x + y = [] ↔ x = [] ∧ y = []; (s) ⊦ a + x = a ' + x; (s)
| y + z = a ' + y0, x ≠ [], z ≠ [], x.last < a, z.head < a, ordered<(x), ordered<(y + z), ¬ x.last < z.head, a ∈ y ∨ a ∈ z ⊦ |
y + z = a ' + y0, z = a0 + x0, x ≠ [], z ≠ [], a0 < a, x.last < a, ordered<(y + z), ordered<(x), ¬ x.last < a0, a ∈ y ∨ a ∈ z ⊦
Used simplifier rules: ⊦ x ≠ [] → (head = x.head ∧ tail = x.tail ↔ x = head + tail); (elim) Used terms: z, a0, x0
| y + z = a ' + y0, z = a0 + x0, x ≠ [], z ≠ [], a0 < a, x.last < a, ordered<(y + z), ordered<(x), ¬ x.last < a0, a ∈ y ∨ a ∈ z ⊦ |
y + a0 ' + x0 = a ' + y0, x ≠ [], a0 < a, x.last < a, ordered<(a ' + y0), ordered<(x), a ∈ y, ¬ x.last < a0 ⊦
Used simplifier rules: ⊦ ¬ a < a; (s) nen: ⊦ ¬ b < a ∧ a = c → ¬ b < c; (forward) from specification weakord[tord] lel: ⊦ a < b ∧ a = c → c < b; (forward) from specification weakord[tord] a: ⊦ (x + y) + z = x + y + z; from specification list ⊦ ¬ a ∈ y → (y + a0 ' + z = a ' + z0 ↔ y = [] ∧ a0 = a ∧ z = z0); (ws) ⊦ a ∈ a0 ' + x ↔ a = a0 ∨ a ∈ x; (s) ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s) nll: ⊦ ¬ b < a ∧ b < c → a < c; (forward) from specification weakord[tord] in-14: ⊦ a ' + x = y → a ∈ y; (forward) from specification list ⊦ a + x = a ' + x; (s) ⊦ a ' ≠ []; (s) ⊦ x + y = [] ↔ x = [] ∧ y = []; (s)
| y + a0 ' + x0 = a ' + y0, x ≠ [], a0 < a, x.last < a, ordered<(a ' + y0), ordered<(x), a ∈ y, ¬ x.last < a0 ⊦ |
y + a0 ' + x0 = a ' + y0, y = a1 + y1, x ≠ [], x.last < a, a0 < a, ordered<(x), ordered<(a ' + y0), a ∈ y, ¬ x.last < a0 ⊦
Used simplifier rules: list('a) freely generated by [], +;; ⊦ [] + x = x; (s) ⊦ a ' + x = a0 ' + y ↔ a = a0 ∧ x = y; (ws) a: ⊦ (x + y) + z = x + y + z; from specification list
| y + a0 ' + x0 = a ' + y0, y = a1 + y1, x ≠ [], x.last < a, a0 < a, ordered<(x), ordered<(a ' + y0), a ∈ y, ¬ x.last < a0 ⊦ |
x ≠ [], x.last < a, a0 < a, ordered<(x), ordered<(a ' + y1 + a0 ' + x0), ¬ x.last < a0 ⊦
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list ⊦ a ∈ a0 ' + x ↔ a = a0 ∨ a ∈ x; (s) ⊦ a + x = a ' + x; (s) ⊦ a ' + x = a0 ' + y ↔ a = a0 ∧ x = y; (ws)
| x ≠ [], x.last < a, a0 < a, ordered<(x), ordered<(a ' + y1 + a0 ' + x0), ¬ x.last < a0 ⊦ |
x = y + a1 ', x ≠ [], a0 < a, a1 < a, ordered<(a ' + y1 + a0 ' + x0), ordered<(x), ¬ a1 < a0 ⊦
Used simplifier rules: x ≠ [] ⊦ a = x.last ∧ y = x.butlast ↔ x = y + a '; (elim) Used terms: x, a1, y
| x = y + a1 ', x ≠ [], a0 < a, a1 < a, ordered<(a ' + y1 + a0 ' + x0), ordered<(x), ¬ a1 < a0 ⊦ |
a1 < a, a0 < a, ordered<(y + a1 '), ordered<(a ' + y1 + a0 ' + x0), ¬ a1 < a0 ⊦
Used simplifier rules: a: ⊦ (x + y) + z = x + y + z; from specification list ⊦ a ' ≠ []; (s) ⊦ x + y = [] ↔ x = [] ∧ y = []; (s)
| a1 < a, a0 < a, ordered<(y + a1 '), ordered<(a ' + y1 + a0 ' + x0), ¬ a1 < a0 ⊦ |
⊦ ¬ a < b ∧ b ∈ x → ¬ ordered<(a ' + x)
Used simplifier rules: ⊦ a ∈ x + y ↔ a ∈ x ∨ a ∈ y; (s) ⊦ a ∈ a0 ' + x ↔ a = a0 ∨ a ∈ x; (s) a: ⊦ (x + y) + z = x + y + z; from specification list transitivity: ⊦ a < b ∧ b < c → a < c; (forward) from specification weakord[tord] Used terms: a0, a, y1 + a0 ' + x0
| ⊦ ¬ a < b ∧ b ∈ x → ¬ ordered<(a ' + x) |
The following image shows the proof tree of sequent calculus. The proved goal is at the bottom. You can click on the nodes to view additional rules. See here for details on colors in a proof tree.