Sign In

Communications of the ACM


A Group Effort

a hypergraph with six hyperedges

Credit: Max Planck Institute

Fifty years ago, mathematician Paul Erdős posed a problem to friends at one of his regular tea parties. The trio thought they would be able to come up with a solution the same afternoon.

It took 49 years for other mathematicians to provide an answer.


No entries found

Log in to Read the Full Article

Sign In

Sign in using your ACM Web Account username and password to access premium content if you are an ACM member, Communications subscriber or Digital Library subscriber.

Need Access?

Please select one of the options below for access to premium content and features.

Create a Web Account

If you are already an ACM member, Communications subscriber, or Digital Library subscriber, please set up a web account to access premium content on this site.

Join the ACM

Become a member to take full advantage of ACM's outstanding computing information resources, networking opportunities, and other benefits.

Subscribe to Communications of the ACM Magazine

Get full access to 50+ years of CACM content and receive the print version of the magazine monthly.

Purchase the Article

Non-members can purchase this article or a copy of the magazine in which it appears.