A Solver for a Theory of Strings and Bit-Vectors
Why this work is in the frame
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Bibliographic record
Abstract
We present the Z3strBV solver for a many-sorted first-order quantifier-free theory Tw, bv of string equations, string length represented as bit-vectors, and bit-vector arithmetic aimed at formal verification, automated testing, and security analysis of C/C++ applications. Our key motivation for building such a solver is the observation that existing string solvers are not efficient at modeling the combined theory over strings and bit-vectors. We demonstrate experimentally that Z3strBV is significantly more efficient than a reduction of string/bit-vector constraints to strings/natural numbers followed by a solver for strings/natural numbers or modeling strings as bit-vectors. We also propose two optimizations. First, we explore the concept of library-aware SMT solving, which fixes summaries in the SMT solver for string library functions such as strlen in C/C++. Z3strBV is able to consume these functions directly instead of re-analyzing the functions from scratch each time. Second, we experiment with a binary search heuristic that accelerates convergence on a consistent assignment of string lengths. We also show that Z3strBV is able to detect nontrivial overflows in real-world system-level code, as confirmed against seven security vulnerabilities from the CVE and Mozilla databases.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it