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Nov
24
comment how we can understand from spectrum of laplacian matrix of a graph that this graph is regular or not .
No, problem. It is ok.
Nov
24
answered prove that we can calculate $\sum^n_{i=1} d^{2}_{i}$ from the spectrum of laplacian matrix of graph.
Nov
24
comment how we can understand from spectrum of laplacian matrix of a graph that this graph is regular or not .
khahesh mikonam che jaleb man fkr mikardam shoma Romanian hastid.
Nov
24
comment how we can understand from spectrum of laplacian matrix of a graph that this graph is regular or not .
@kpax your welcome. May be this paper helps you:Which graphs are determined by their spectrum? by Dam and Haemers.
Nov
24
answered how we can understand from spectrum of laplacian matrix of a graph that this graph is regular or not .
Nov
24
reviewed Reject How to determine whether the following sets are countable:
Nov
24
reviewed Approve Simple problem about Laplace Equation in a domain
Nov
20
awarded  Enlightened
Nov
20
awarded  Nice Answer
Nov
20
comment The limit of $\tan(n)$
I like your proof.
Nov
20
revised The limit of $\tan(n)$
edited body
Nov
20
comment The limit of $\tan(n)$
It is one of my favorite problem of calculus.
Nov
20
answered The limit of $\tan(n)$
Nov
17
reviewed Approve Prove that for a real matrix $A$, $\ker(A) = \ker(A^TA)$
Nov
6
reviewed Approve annual and effective annual interest rate
Nov
5
reviewed Approve A proof involving Fermat's Little Theorem.
Nov
4
reviewed Reject Help to compute all powers $A^{n}$ and find is the matrix of $A$ diagonal?
Nov
4
comment Prove isomorphism for a commutative ring
For instance, you want to define $\phi(r)$ by using $\phi(1)=m$. So u can see that $\phi(r)=r\phi(1)=r.m$. Is it clear?
Nov
4
answered Prove isomorphism for a commutative ring
Nov
2
reviewed Approve question about normal subgroup and question about notation