  In a resonance model the reactions pi N -> Y K and pi Delta -> Y K are
studied. For the reactions pi N -> Lambda K and pi Delta -> Lambda K, the
resonances N(1650)(J^P=1/2^-), N(1710)(1/2^+) and N(1720)(3/2^+) are included
as intermediate states. For the reactions pi N -> Sigma K, the resonances
N(1710)(1/2^+), N(1720)(3/2^+) and Delta(1920)(3/2^+) are considered, while for
the pi Delta -> Sigma K reactions the intermediate resonances are
N(1710)(1/2^+) and N(1720)(3/2^+). Besides these resonances in the s-channel,
the t-channel K^*(892) exchanges are also taken into account as a smooth
background. The relevant coupling constants for the meson-baryon vertices are
obtained (except for Delta(1920)) from the experimental decay branching ratios
of the relevant resonances. All isospin channels of the pi N -> Y K and pi
Delta -> Y K cross sections are calculated. By comparing the calculated results
with the available experimental data, we find that the total cross sections of
the pi N -> Y K reactions can be explained by the resonance model. The pi Delta
-> Y K cross sections, for which no experimental data are available, are
predicted theoretically. Parametrizations of the calculated total cross
sections for all different isospin channels are given for the use of kaon
productions in heavy ion collisions. The differential cross sections are also
studied.
