forest
an acyclic graph is called a forest.
[cite:;taken from @graph_diestel_2017 chapter 1.5 trees and forests]
[cite:;taken from @graph_diestel_2017 chapter 1.5 trees and forests]
a forest of 
is a spanning forest if every pair of vertices that are connected in are also connected in 
. a spanning forest that is a tree is called a spanning tree.
[cite:;taken from @graph_klein_2024 chapter 3.1 spanning forests and trees]
is a spanning forest if every pair of vertices that are connected in are also connected in . a spanning forest that is a tree is called a spanning tree.[cite:;taken from @graph_klein_2024 chapter 3.1 spanning forests and trees]
let 
be spanning forest of . an edge of is a tree edge with respect to if 
belongs to , and otherwise is a nontree edge.
[cite:;taken from @graph_klein_2024 chapter 3.1 spanning forests and trees]
be spanning forest of . an edge of is a tree edge with respect to if belongs to , and otherwise is a nontree edge.[cite:;taken from @graph_klein_2024 chapter 3.1 spanning forests and trees]