mathlib

d3abacf0 - feat(combinatorics/simple_graph/connectivity): `is_bridge` and cycle characterization (#17306)

feat(combinatorics/simple_graph/connectivity): `is_bridge` and cycle characterization (#17306) Definition of bridge edges in terms of whether removing the edge makes its incident vertices unreachable from one another, and a characterization of bridge edges as their never being an edge of a cycle. From the `walks_and_trees` branch.