4×n Chomp P-positions: Complete tabulation for n ≤ 500

Complete tabulation of all P-positions (losing positions for the player to move) in 4×n Chomp for all board sizes n ≤ 500. Contains 4,316,097 P-positions stored as tuples (a, b, c, d) with a≥b≥c≥d≥0, where each coordinate gives the number of remaining squares in the corresponding row. Generated using an optimized C++ solver with bitpacked uint64_t state representation. Verified against known 2×n and 3×n ground truth results. Related paper: "Structural Conjectures for 4×n Chomp: Unique Extension, Asymptotic Ratios, and Period-112 Geometry" (preprint, 2026). Files:- p_positions_4xn_cpp_500.csv: All 4,316,097 P-positions, columns a,b,c,d- chomp.cpp: C++ solver source code- verify.py: Verification script