Discussion #9524 reported systematic TPTP result polarity errors
(notably `Unsatisfiable/Theorem` cases returned as `Satisfiable`) and
timeout-path instability in the frontend. The dominant issue was
semantic: free variables in FOF/CNF formulas were parsed as constants
instead of implicitly universally quantified variables.
- **Parser semantics: free variables now follow TPTP rules**
- In `/home/runner/work/z3/z3/src/cmd_context/tptp_frontend.cpp`, free
variables encountered while parsing an annotated formula are now
collected in formula scope and wrapped with a top-level `forall`.
- This applies to both term and atomic-formula paths, so variable
occurrences are treated consistently.
- Explicitly bound quantifier variables continue to take precedence over
implicit ones.
- **Scoped implementation cleanup**
- Added scoped state for implicit-variable collection to avoid leaking
parser state across formulas.
- Kept variable binding order stable so quantifier construction is
deterministic.
- **Timeout-path robustness**
- Updated frontend exception catches to `const&` in the TPTP stream
entrypoint to make timeout/error handling behavior consistent with
thrown exception forms.
- **Regression tests**
- Extended `/home/runner/work/z3/z3/src/test/tptp.cpp` with focused
cases for:
- FOF free-variable implicit universal quantification.
- CNF free-variable implicit universal quantification.
```tptp
cnf(c1,axiom, p(X)).
cnf(c2,axiom, ~ p(a)).
```
This now maps to `forall X. p(X)` plus `~p(a)`, yielding `% SZS status
Unsatisfiable` as expected.
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>
This PR targets the main TFF frontend parsing failures: bare numeric
atoms were being treated as uninterpreted terms (`U`) in formula
position, decimal literals were not parsed, and `$uminus` was not
recognized as an arithmetic builtin. These issues caused widespread
parse/type failures in arithmetic-heavy TPTP inputs.
- **Numeric atom parsing in formulas (TFF)**
- Added a shared numeric-literal parser path for term/formula contexts.
- In atomic formulas, numeric LHS now parses as arithmetic numerals
before `=`/`!=` handling, avoiding `U` vs `Int/Real` mismatches.
- **Decimal literal support**
- Extended numeral parsing to accept `d.d` forms and construct `Real`
numerals.
- Keeps existing integer (`d`) and rational (`d/d`) behavior on the same
code path.
- **`$uminus` builtin support**
- Added explicit handling for `$uminus(<arg>)` in term parsing.
- Enforces arity 1 and arithmetic-argument checks; maps directly to
arithmetic unary minus.
- **Focused regression coverage**
- Added/updated TPTP unit cases for:
- bare integer inequality: `31 != 12`
- decimal arithmetic literal usage
- `$uminus` in arithmetic predicates
Example of now-supported inputs:
```tptp
tff(c1,conjecture, 31 != 12).
tff(c2,conjecture, ~ $less(-3.25,-8.69)).
tff(c3,conjecture, $less($uminus(2),0)).
```
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>
