Decoupling Generation and Selection for Budget-Constrained Faithful Summarization
This work addresses the challenges of factual inconsistency, redundancy, and weak length control in multi-document abstractive summarization by proposing a modular generate-then-select framework. Under a sentence-level budget constraint, the approach first employs a pretrained model to generate candidate summaries and decomposes them into sentence units; it then applies a combinatorial optimization selector to jointly maximize relevance, factual faithfulness, and diversity while minimizing redundancy. By decoupling generation from selection, the framework flexibly integrates various selection strategies—such as MMR, ILP, and DPP-inspired objectives—without requiring fine-tuning of the generator. Experimental results demonstrate significant improvements in factual consistency and source fidelity across CNN/DailyMail, Multi-News, FaithBench, and TofuEval benchmarks. Human evaluations further confirm consistent superiority over baselines in coherence, relevance, clarity, and conciseness, with only a marginal drop in ROUGE scores.