Skills › Research & Science › Math
prove
Prove validity of logical statements by negation and satisfiability checking. If the negation is unsatisfiable, the original statement is valid. Otherwise a counterexample is returned.
The full skill
—
name: prove
description: Prove validity of logical statements by negation and satisfiability checking. If the negation is unsatisfiable, the original statement is valid. Otherwise a counterexample is returned.
—
Given a conjecture (an SMT-LIB2 assertion or a natural language claim), determine whether it holds universally. The method is standard: negate the conjecture and check satisfiability. If the negation is unsatisfiable, the original is valid. If satisfiable, the model is a counterexample.
# Step 1: Prepare the negated formula
Action:
Wrap the conjecture in `(assert (not …))` and append
`(check-sat)(get-model)`.
Expectation:
A complete SMT-LIB2 formula that negates the original conjecture with
all variables declared.
Result:
If the negation is well-formed, proceed to Step 2.
If the conjecture is natural language, run **encode** first.
Example: to prove that `(> x 3)` implies `(> x 1)`:
“`smtlib
(declare-const x Int)
(assert (not (=> (> x 3) (> x 1))))
(check-sat)
(get-model)
“`
# Step 2: Run the prover
Action:
Invoke prove.py with the conjecture and variable declarations.
Expectation:
The script prints `valid`, `invalid` (with counterexample), `unknown`,
or `timeout`. A run entry is logged to z3agent.db.
Result:
On `valid`: proceed to **explain** if the user needs a summary.
On `invalid`: report the counterexample directly.
On `unknown`/`timeout`: try **simplify** first, or increase the timeout.
“`bash
python3 scripts/prove.py –conjecture "(=> (> x 3) (> x 1))" –vars "x:Int"
“`
For file input where the file contains the full negated formula:
“`bash
python3 scripts/prove.py –file negated.smt2
“`
With debug tracing:
“`bash
python3 scripts/prove.py –conjecture "(=> (> x 3) (> x 1))" –vars "x:Int" –debug
“`
# Step 3: Interpret the output
Action:
Read the prover output to determine validity of the conjecture.
Expectation:
One of `valid`, `invalid` (with counterexample), `unknown`, or `timeout`.
Result:
On `valid`: the conjecture holds universally.
On `invalid`: the model shows a concrete counterexample.
On `unknown`/`timeout`: the conjecture may require auxiliary lemmas or induction.
# Parameters
| Parameter | Type | Required | Default | Description |
|———–|——|———-|———|————-|
| conjecture | string | no | | the assertion to prove (without negation) |
| vars | string | no | | variable declarations as "name:sort" pairs, comma-separated |
| file | path | no | | .smt2 file with the negated formula |
| timeout | int | no | 30 | seconds |
| z3 | path | no | auto | path to z3 binary |
| debug | flag | no | off | verbose tracing |
| db | path | no | .z3-agent/z3agent.db | logging database |
Either `conjecture` (with `vars`) or `file` must be provided.