Improving Compactness and Reducing Ambiguity of CFIRE Rule-Based Explanations
Sebastian Müller, Tobias Schneider, Ruben Kemna, Vanessa Toborek
TL;DR
The paper addresses inter-class ambiguity in CFIRE's rule-based explanations for tabular data by introducing ThresholdPruning, a post-hoc procedure that uses per-term win counts $Wins[t]$ and a tolerance $\theta$ to trim the global rule set $E$ while controlling relative accuracy on a reference set $X$. Safe pruning with $\theta=0$ preserves predictive performance while reducing both model size and cross-class conflicts, and modest pruning with $\theta=0.05$ achieves additional gains with only minor F1 loss (typically $<2\%$). Across 700 networks and 14 tasks using three local explainers, pruning yields large reductions in ambiguity and compactness, particularly for larger CFIRE models, with some tasks remaining inherently ambiguous. These findings support deploying CFIRE with a pruning extension to produce clearer, more compact explanations without sacrificing accuracy.
Abstract
Models trained on tabular data are widely used in sensitive domains, increasing the demand for explanation methods to meet transparency needs. CFIRE is a recent algorithm in this domain that constructs compact surrogate rule models from local explanations. While effective, CFIRE may assign rules associated with different classes to the same sample, introducing ambiguity. We investigate this ambiguity and propose a post-hoc pruning strategy that removes rules with low contribution or conflicting coverage, yielding smaller and less ambiguous models while preserving fidelity. Experiments across multiple datasets confirm these improvements with minimal impact on predictive performance.
