counterexample for cycles in a graph
94928
Every $k$ vertices in an $k$ - connected graph are contained in a cycle.
39753
Proving that in a simple graph with $n$ vertices, two vertices have the same degree
78243
graph-theory problem about outdegree and indegree
17268
Cycles in permutations of a given size
91777
Product of Non-Disjoint Cycles
129752
How to find whether it is possible for each vertex of a graph to have a different degree?
114773
counterexamples on modules
142861
Multipartite graphs which are not planar
18383
List of ways to tell if degree sequence is impossible for a simple graph
3663
Finding counterexamples in elementary set theory.
65639
Existence of a self-complementary graph
145818
Edges on an even number of Hamilton cycles
97630
A graph which is not a single block has at least two leaf blocks
131137
If ${\lvert{E(G)}\rvert}>{\lvert{V(G)}\rvert}+3$, graph $G$ has at least two disjoint cycles.
19219
On the invertibility of the adjacency matrix of a graph
140199
Proof that disjoint cycles commute
101520
Let $G$ be a graph of minimum degree $k>1$. Show that $G$ has a cycle of length at least $k+1$