arXiv subjects

Soohan Lim

Publications and source records attributed to Soohan Lim.

5 recordsLinked to original sources

arXiv2026

SLICE: Specification-Level Isolation of Contract Enforcement

Programming problems commonly specify both the computation a function should perform and the conditions that its inputs must satisfy. Large language models are widely used to generate code from these problem specifications, and the generated function must implement the required computation while enforcing the stated input conditions. The stated input conditions collectively form an input contract. Enforcing this contract is difficult: incomplete enforcement accepts inputs that should be rejected, whereas overly restrictive enforcement rejects inputs that should be accepted. Existing code generation methods do not provide a generation process that identifies both the input contract and the functional requirements and generates code that satisfies them jointly. We therefore introduce SLICE, a generation framework that identifies both requirements and addresses them through separate generation stages. SLICE consists of three stages: (i) Graph-based specification structuring, which grounds contract conditions to description segments in a specification graph and removes contract-only segments to form a functional view; (ii) Functional body generation, which produces multiple candidate function bodies through greedy and sampled decoding, ranks them using execution scores, and resolves ties using difference-region log probabilities; and (iii) Contract assertion generation, which generates input-validation assertions from the identified contract conditions and attaches them to the selected function body. We evaluate SLICE on ContractEval across four LLMs and compare it with six competing methods. Relative to the strongest evaluated baseline for each model, SLICE improves performance in generating code that satisfies both the functional requirements and the input contract by an average of 6.58%. Our code is available at https://github.com/suhanmen/SLICE.

cs.SE↗

arXiv2026

STAB: Specification-driven Testing for Algorithmic Bottlenecks

Evaluating the efficiency of algorithmic code requires test cases that expose runtime bottlenecks. Previous methods generate efficiency test cases either by increasing input size or by generating code-specific inputs that make the given implementation run slowly. Consequently, they do not address the structural input conditions that drive the algorithmic worst case. We introduce STAB, a specification-driven pipeline that generates test cases that expose algorithmic bottlenecks from a natural-language problem specification alone. STAB separates the task into constraint-bound maximization and adversarial structure injection. (i) The constraint saturator extracts constraints and resolves large admissible size assignments using rule-based saturation and CP-SAT optimization over related variables. (ii) The adversarial scenario injector retrieves implementation-level adversarial construction principles from a curated scenario catalog using keyword matching and K-nearest neighbors (KNN). STAB encodes the problem specification, resolved boundary, and retrieved construction principles into a structured generation specification, from which the LLM synthesizes a Python test case generator. On CodeContests, STAB raises the rate of generated test cases that expose algorithmic bottlenecks from 50.43% to 73.45% on average across open-source LLMs and from 57.45% to 71.85% on average across closed-source LLMs, with consistent gains across Python, Java, and C++. Our code is available at https://github.com/suhanmen/STAB.

cs.AI↗

arXiv2025

ContractEval: A Benchmark for Evaluating Contract-Satisfying Assertions in Code Generation

Current code generation evaluation measures functional correctness on well-formed inputs that satisfy all input preconditions. This paradigm has a critical limitation: task descriptions often leave these preconditions implicit, while evaluation filters out inputs that violate them. As a result, generated code may achieve high pass@k scores while failing to enforce the preconditions that the task actually requires. To address this gap, we introduce ContractEval, a benchmark for evaluating whether generated code enforces such preconditions--commonly referred to as contracts. Built on HumanEval+ and MBPP+, ContractEval consists of 364 tasks, each with three components: (i) descriptions reconstructed to explicitly state the contracts, (ii) test cases synthesized through a neuro-symbolic pipeline that pairs an LLM with an SMT solver to evaluate whether generated code satisfies these contracts, and (iii) reference code combined with contracts. Using ContractEval to evaluate five representative open-source code LLMs, we reveal a stark disparity between functional correctness and contract satisfaction. Under standard prompting, these models achieve pass@1 of 75-82% with 0% contract satisfaction. Even when contracts are explicitly stated in the prompt, the satisfaction rate reaches only 23-41%. This indicates that current LLMs struggle to satisfy contracts in their generated code, establishing contract satisfaction as a crucial and previously overlooked axis of code generation quality. Our code is available at https://github.com/suhanmen/ContractEval.

cs.AI↗

arXiv2025

MEC$^3$O: Multi-Expert Consensus for Code Time Complexity Prediction

Predicting the complexity of source code is essential for software development and algorithm analysis. Recently, Baik et al. (2025) introduced CodeComplex for code time complexity prediction. The paper shows that LLMs without fine-tuning struggle with certain complexity classes. This suggests that no single LLM excels at every class, but rather each model shows advantages in certain classes. We propose MEC$^3$O, a multi-expert consensus system, which extends the multi-agent debate frameworks. MEC$^3$O assigns LLMs to complexity classes based on their performance and provides them with class-specialized instructions, turning them into experts. These experts engage in structured debates, and their predictions are integrated through a weighted consensus mechanism. Our expertise assignments to LLMs effectively handle Degeneration-of-Thought, reducing reliance on a separate judge model, and preventing convergence to incorrect majority opinions. Experiments on CodeComplex show that MEC$^3$O outperforms the open-source baselines, achieving at least 10% higher accuracy and macro-F1 scores. It also surpasses GPT-4o-mini in macro-F1 scores on average and demonstrates competitive on-par F1 scores to GPT-4o and GPT-o4-mini on average. This demonstrates the effectiveness of multi-expert debates and weight consensus strategy to generate the final predictions. Our code and data is available at https://github.com/suhanmen/MECO.

cs.AI↗

arXiv2025

TCProF: Time-Complexity Prediction SSL Framework

Time complexity is a theoretic measure to determine the amount of time the algorithm needs for its execution. In reality, developers write algorithms into code snippets within limited resources, making the calculation of a code's time complexity a fundamental task. However, determining the precise time complexity of a code is theoretically undecidable. In response, recent advancements have leaned toward deploying datasets for code time complexity prediction and initiating preliminary experiments for this challenge. We investigate the challenge in low-resource scenarios where only a few labeled instances are given for training. Remarkably, we are the first to introduce TCProF: a Time-Complexity Prediction SSL Framework as an effective solution for code time complexity prediction in low-resource settings. TCProF significantly boosts performance by integrating our augmentation, symbolic modules, and a co-training mechanism, achieving a more than 60% improvement over self-training approaches. We further provide an extensive comparative analysis between TCProF, ChatGPT, and Gemini-Pro, offering a detailed evaluation of our approach. Our code is at https://github.com/peer0/few-shot-tc.

cs.SE↗