SynMQG: Disentanglement and Mutual-Information Optimization for Synergistic Multi-modal Question Generation

Synergistic multi-modal question generation aims to generate questions grounded in synergistic semantics distributed across multiple modalities, rather than being specified by isolated information from any single modality alone. In this setting, modality-specific cues and cross-modal shared semantics must be jointly well-organized so that the generated question reflects synergistic multi-modal contribution and captures genuinely synergistic information. However, this task faces two core challenges: how to disentangle multi-modal information for synergistic information modeling, and how to preserve synergistic contribution during question generation. To address these challenges, we propose SynMQG, a synergistic dependency-aware framework derived from a mutual-information-based theoretical analysis, which integrates disentangled representation learning with synergy-aware optimization for synergistic multi-modal question generation. Specifically, SynMQG disentangles the multi-modal context into visual-specific, textual-specific, and shared semantics, thereby explicitly organizing heterogeneous information for synergistic information modeling. Based on these disentangled representations, it further introduces a reasoning chain as an intermediate scaffold to structure cross-modal information before generation. Moreover, SynMQG proposes GRPO with a mutual-information-based synergy reward, which explicitly measures whether the generated question preserves effective contribution of synergistic information, encouraging the model to generate questions that depend on synergistic multi-modal semantics rather than superficial single-modal cues. Experiments on ScienceQA and MultimodalQA show that SynMQG consistently outperforms representative MQG baselines across standard text-generation metrics, MLLM-based evaluation, and human evaluation, while generating questions with stronger synergistic multi-modal grounding and higher multi-modal dependency. The source code is available at https://anonymous.4open.science/r/MQG-8E57.