Wikipedia:Reference desk/Archives/Mathematics/2022 March 19

= March 19 =

Dissemination problem
Consider $$ n $$ people, each of whom knows a particular fact. How many two-person meetings are required for everybody to know everything, where at each meeting everything known to date is shared? I can't get below $$ 2n-3 $$, achieved in this way, for example: person $$ 1 $$ meets everyone else up to person $$ n $$ (taking $$ n-1 $$ meetings), then re-meets everyone from $$ 2 $$ to $$ n-1 $$ (taking $$ n-2 $$ meetings). Is it possible to do the job in fewer, or indeed to prove that $$ 2n-3 $$ is the lowest number? →2A00:23C6:AA07:4C00:4C7E:441:A97:15A2 (talk) 13:30, 19 March 2022 (UTC)


 * It is certainly possible to do better in general: with $$n = 4$$, for example, the meetings AB, CD, AC, BD work. But in fact you only get that one bit of improvement: see https://oeis.org/A058992 . -- JBL (talk) 15:47, 19 March 2022 (UTC)