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If you have any good math exercises to share feel free to contribute them on http://exwiki.org


2d
comment Adding an edge and a vertex to non-isomorphic graphs
@chowching Yes in that case you are right.
2d
comment Adding an edge and a vertex to non-isomorphic graphs
Intuitively, two vertices are in the same orbit if they are "indistinguishable" in other words any isomorphism from $G$ to $H$ only can map a vertex to vertices in the same orbit.
2d
comment Adding an edge and a vertex to non-isomorphic graphs
Its not necessarily the union. Take $G = H$ to be the Petersen graph. Then $Aut(G\cup H)$ only has 1 orbit.
2d
revised Adding an edge and a vertex to non-isomorphic graphs
added 9 characters in body
2d
answered Adding an edge and a vertex to non-isomorphic graphs
Jan
20
answered Graph Theory Software with simple GUI
Jan
19
comment Can we say anything about the order of the second largest eigen-value?
You should then try to figure something out of the formula for the eigenvalues of a vt graph. Note that in general vertex transitive does not give you much of a difference. There are pairs of vertex transitive and not vertex transitive regular graphs with the same value of your expression.
Jan
19
answered Can we say anything about the order of the second largest eigen-value?
Jan
11
comment Path cover in directed graphs
What it says is that on each of the paths of $\mathcal{P}$ you can pick a vertex so that the resulting vertices will be mutually non-adjacent.
Dec
12
awarded  Yearling
Dec
11
accepted Average number of linear factors in a monic polynomial of degree $n$ over $\mathbb{F}_p$
Dec
7
revised Semi-hamiltonian graph.
deleted 9 characters in body
Dec
7
comment Semi-hamiltonian graph.
@user180834 I wrote a complete solution.
Dec
7
revised Semi-hamiltonian graph.
added 166 characters in body
Dec
7
comment Semi-hamiltonian graph.
@user180834 Can you answer the question in the hint?
Dec
7
answered Semi-hamiltonian graph.
Dec
7
comment Semi-hamiltonian graph.
What do you mean by semi-Hamiltonian?
Dec
4
asked Average number of linear factors in a monic polynomial of degree $n$ over $\mathbb{F}_p$
Nov
29
comment Diameter of a Connected Graph
@sam_rox Yes, you are right. Thanks for the remark, I've corrected the page.
Nov
21
accepted Determinant of the Kronecker product involving the identity