Commit 2025-11-25 09:29 aef322b8

feat(Combinatorics/SimpleGraph): split Walk.lean into 5 files (#31573) Split into 5 files in a new Walks subfolder:

• Basic.lean: basic definitions and theorems about them, without modifying the walks: Walk, Nil, length, support, darts, edges, edgeSet
• Traversal.lean: access parts of a walk: getVert, snd, penultimate, firstDart, lastDart
• Operations.lean: similar to the existing WalkDecomp.lean, this file defines operations on walks: copy, append, concat, reverse, drop, take, tail, dropLast. The name of the file matches SimpleGraph/Operations.lean which defines operations on graphs.
• Maps.lean: operations that map the walk to another graph: map, mapLe, transfer, induce, toDeleteEdges, toDeleteEdge. The name of the file matches SimpleGraph/Maps.lean which defines maps on graphs.
• Subwalks.lean: the definition of IsSubwalk and theorems about it Deprecates the original Walk.lean module.