S1,S2,...,Sm have a SDR dinstinct x1∈S1,c2∈S2,.,cm∈Sm VIC{1,2,.,m, UcS≥|{x|i∈Il≥I. distinctS1, S2,...,Sm have a SDR ⇥ dinstinct x1 ￾ S1, x2 ￾ S2,...,xm ￾ Sm ⇥I ￾ {1, 2,...,m}, ￾ ￾ ⇥ i￾I Si ￾ ￾ ￾ |{x ￾ |I|. i | i ⇥ I}| distinct