Learning to Reason for Hallucination Span Detection - Su, Hsuan; Hu, Ting-Yao; Koppula, Hema Swetha; Krishna, Kundan; Pouransari, Hadi; Hsieh, Cheng-Yu; Koc, Cem; Cheng, Joseph; Tuzel, Oncel; Vemulapalli, Raviteja (International Conference on Learning Representations, 2026)