arXiv subjects

Ricardo Brancas

Publications and source records attributed to Ricardo Brancas.

6 recordsLinked to original sources

arXiv2026

What Bugs Do Prolog Students Write? An Empirical Taxonomy and Data-Driven Mutation Framework

Automated feedback tools for logic programming education depend on realistic bug datasets that reflect the mistakes students actually make. However, existing mutation testing frameworks for Prolog treat all mutations as equally likely, producing synthetic faults that diverge from classroom reality. We present an empirical study of 7,201 Prolog submissions from 265 undergraduate students, from which we derive a fine-grained taxonomy of student bugs through manual classification of 200 bug-fixing submissions. Guided by this taxonomy, we develop LogMorph, a data-driven mutation tool whose 17 operators are weighted according to the observed error distribution. LogMorph enumerates valid mutation sites on the abstract syntax tree, samples operators proportionally, injects faults, delegating to an SMT-based synthesizer when new code fragments are needed, and validates each mutant against a reference test suite. An evaluation of 16,000 generated mutants shows that the synthetic error distribution closely matches the student distribution, with most bug categories agreeing to within two percentage points. We identify cut-related mutations and synthesizer-generated code as the main sources of residual divergence, and outline how combining the SMT back-end with a language model fine-tuned on student code can further improve realism.

cs.LO↗

arXiv2026

Can Automated Feedback Turn Students into Happy Prologians?

Providing personalized feedback is essential for effective learning, but delivering it promptly can be challenging in large-scale courses. In this work, we present ProHelp, an automated assessment platform for Prolog built on top of the GitSeed framework, and we evaluate it through a survey of 144 students from a 365-student undergraduate logic programming course. We assessed the perceived usefulness of seven types of automated feedback, including automatic testing, predicate scoring, syntax error highlighting, open choice point warnings, score rankings, solution type validation, and unknown predicate name suggestions. Our results show that 74% of students agreed the feedback helped increase their grade, and the system achieved a System Usability Scale score of 78.5 (grade B+). Among the feedback types, automatic testing was ranked as the most useful, followed by open choice point warnings and predicate scoring, with statistically significant differences. We found no significant effect of students' interest level, engagement with optional exercises, or use of large language models on their perception of feedback usefulness. We also explore student preferences for future feedback features, finding a significant preference for showing the differences between generated and expected test outputs.

cs.SE↗

arXiv2026

ProDebug: An Automated Debugging System for Prolog

Prolog is a well-known declarative programming language commonly used in introductory courses on logic and reasoning. However, many students find Prolog challenging because it lacks the familiar debugging mechanisms found in imperative languages. In large classes, this difficulty is exacerbated by the challenge of providing timely and personalized feedback to students. In this work, we introduce ProDebug, the first tool to combine Large Language Models (LLMs) with spectrum-based and mutation-based techniques for automated debugging of Prolog assignments. ProDebug automatically identifies faults and proposes bug repairs for student Git submissions. Faults are detected using three approaches--spectrum-based, mutation-based, and LLM reasoning--while repairs are generated using mutation-based techniques and LLMs. Our evaluation on 1499 buggy student submissions from a bachelor's level programming class demonstrates the potential of automated, LLM-augmented feedback systems to scale support for declarative programming education.

cs.PL↗

arXiv2024

Combining Logic with Large Language Models for Automatic Debugging and Repair of ASP Programs

Logic programs are a powerful approach for solving NP-Hard problems. However, due to their declarative nature, debugging logic programs poses significant challenges. Unlike procedural paradigms, which allow for step-by-step inspection of program state, logic programs require reasoning about logical statements for fault localization. This complexity is amplified in learning environments due to students' inexperience. We introduce FormHe, a novel tool that combines logic-based techniques and Large Language Models to identify and correct issues in Answer Set Programming submissions. FormHe consists of two components: a fault localization module and a program repair module. First, the fault localizer identifies a set of faulty program statements requiring modification. Subsequently, FormHe employs program mutation techniques and Large Language Models to repair the flawed ASP program. These repairs can then serve as guidance for students to correct their programs. Our experiments with real buggy programs submitted by students show that FormHe accurately detects faults in 94% of cases and successfully repairs 58% of incorrect submissions.

cs.SE↗

arXiv2024

CUBES: A Parallel Synthesizer for SQL Using Examples

In recent years, more people have seen their work depend on data manipulation tasks. However, many of these users do not have the background in programming required to write complex programs, particularly SQL queries. One way of helping these users is automatically synthesizing the SQL query given a small set of examples. Several program synthesizers for SQL have been recently proposed, but they do not leverage multicore architectures. This paper proposes CUBES, a parallel program synthesizer for the domain of SQL queries using input-output examples. Since input-output examples are an under-specification of the desired SQL query, sometimes, the synthesized query does not match the user's intent. CUBES incorporates a new disambiguation procedure based on fuzzing techniques that interacts with the user and increases the confidence that the returned query matches the user intent. We perform an extensive evaluation on around 4000 SQL queries from different domains. Experimental results show that our sequential version can solve more instances than other state-of-the-art SQL synthesizers. Moreover, the parallel approach can scale up to 16 processes with super-linear speedups for many hard instances. Our disambiguation approach is critical to achieving an accuracy of around 60%, significantly larger than other SQL synthesizers.

cs.PL↗

arXiv2023

On Repairing Natural Language to SQL Queries

Data analysts use SQL queries to access and manipulate data on their databases. However, these queries are often challenging to write, and small mistakes can lead to unexpected data output. Recent work has explored several ways to automatically synthesize queries based on a user-provided specification. One promising technique called text-to-SQL consists of the user providing a natural language description of the intended behavior and the database's schema. Even though text-to-SQL tools are becoming more accurate, there are still many instances where they fail to produce the correct query. In this paper, we analyze when text-to-SQL tools fail to return the correct query and show that it is often the case that the returned query is close to a correct query. We propose to repair these failing queries using a mutation-based approach that is agnostic to the text-to-SQL tool being used. We evaluate our approach on two recent text-to-SQL tools, RAT-SQL and SmBoP, and show that our approach can repair a significant number of failing queries.

cs.DB↗