Verified Stallings folding for finitely generated subgroups of F2

Source: url:https://github.com/Arthur742Ramos/stallings-folding/tree/117dde0a8415d3da1787e15ad22a6223a744432d Authors: Arthur Freitas Ramos Status: verified Main declarations: Stallings.folded_recognizer_exists Tags: free-groups, stallings-folding, finite-automata, verified-algorithms MSC: 20E05, 68Q45, 03B35