  Short-range parts of the baryon-baryon ($BB$) interactions are analyzed from
the spin-flavor $SU(6)_{sf}\supset SU(3)_f \times SU(2)_s$ symmetry viewpoint.
Due to the Pauli principle of quarks, the symmetry structure of the wave
functions is restricted at short distances. Consequently, the $BB$ states with
the same spin-flavor quantum numbers may be reduced into one or a few
spin-flavor states. Such reduction causes repulsion and/or suppression of
transitions at short distances. We show that the observed suppression of the
$\Xi N \to \Lambda\Lambda$ conversion can be explained following the above
argument. It is also applied to the suppression of the $\Sigma N$ to $\Lambda
N$ conversion in the spin 1 and isospin 1/2 channel. Furthermore, the effects
of the color-magnetic interaction (CMI), which prefers flavor antisymmetric
states, to the Pauli-allowed states are discussed.
