Consequences of Crossing Symmetry in SU3

The following processes of 2 octets transforming into 2 octets are discussed on the basis of crossing symmetry; $P+B\to P+B$, $B+B\to B+B$, $P+V\to P+V, \cdots$ and their crossed channels, where $B$, $P$, and $V$ represent baryons, pseudoscalar mesons, and vector mesons, respectively. The relation between channel amplitudes, the number of independent channel amplitudes, and spin selection rules are systematically obtained.