✐‹creator "Kevin Kappelmann"› section ‹Positions› theory Zippy_Positions imports ML_Alternating_Zipper_Paths Zippy_Nodes begin ML_file‹zippy_positions_mixin_base.ML› ML_file‹zippy_positions_mixin.ML› ML_file‹zippy_node_positions_mixin_base.ML› end