Strangeness production in pp and pn reactions at COSY

The cooler synchrotron COSY-Jülich delivers phase-space cooled, polarized proton and deuteron beams with momenta up to p=3.65GeV/c. Various experiments on hadron-induced strangeness production on proton, neutron and nuclear targets have been carried out. Here we report recent results on associated strangeness production in pp→KYN (Y=Λ,Σ) reactions, on K+-production in pn collisions, and on KK¯-pair production in pp interactions. We also briefly discuss possible measurements to disentangle the parity of the recently discovered pentaquark state Θ+, the spin dependence of the YN interaction, as well as planned experiments which aim at the determination of the a0-f0 mixing matrix element, a quantity which is believed to be sensitive to the nature of the light scalar mesons a0/f0(980).