A discrete isodiametric result: the Erd\H{o}s-Ko-Rado theorem for   multisets
  There are many generalizations of the Erd\H{o}s-Ko-Rado theorem. We give new results (and problems) concerning families of $t$-intersecting $k$-element multisets of an $n$-set and point out connections to coding theory and classical geometry. We establish the conjecture that for $n \geq t(k-t)+2$ such a family can have at most ${n+k-t-1\choose k-t}$ members. 
Zolt\'an F\"uredi, D\'aniel Gerbner, M\'at\'e Vizer
math.CO