25 Oct '02 22:29

This isn't my problem, it was given to me by my one of my lecturers. Rumour has it that

you can count the number of undergraduates in the whole of Cambridge who've cracked this

one on one hand. Here goes...

Each of n elderly dons knows a piece of gossip not known to any of the others. They

communicate by telephone, and in each call the two dons concerned reveal to each other all

the information they know so far. What is the smallest number of calls that can be made in

such a way that, at the end, all the dons know all the gossip?

you can count the number of undergraduates in the whole of Cambridge who've cracked this

one on one hand. Here goes...

Each of n elderly dons knows a piece of gossip not known to any of the others. They

communicate by telephone, and in each call the two dons concerned reveal to each other all

the information they know so far. What is the smallest number of calls that can be made in

such a way that, at the end, all the dons know all the gossip?