Take the 2-minute tour ×
MathOverflow is a question and answer site for professional mathematicians. It's 100% free, no registration required.

is any strongly regular graph a regular two-graph?

two-graph:a two graph is a collection $B$ of 3-subsets a set $X$ with the property that, for any 4-subset $Y$ of $X$, an even numbers of $B$ belong to $Y$.

regular two-graph:a two-graph is regular if it is a 2-design (with parameters $2-(n,3,\lambda)$ for some $\lambda$ )

share|improve this question
add comment

2 Answers

up vote 5 down vote accepted

No, there is a correspondence between certain strongly regular graphs and two-graphs but those strongly regular graphs have specific and restricted parameters.

share|improve this answer
add comment

ok, that's right, if $\Gamma$ is strongly regular graph with parameters $(v,k,\lambda,\mu)$ then it's regular two-graph if and only if $k=2\mu$

share|improve this answer
add comment

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.