2604.01304 Distance-Regular Graphs with Intersection Number a_1 = 0 Are Classified for Diameter d >= 7
We establish a new result in algebraic geometry and combinatorics: distance-regular graphs with intersection number a_1 = 0 are classified for diameter d >= 7. Our proof introduces a novel filtration technique combined with deformation-theoretic arguments that resolve a long-standing open question in the field.