Applications for workshops within the BIRS-IMAG program are made in the general call for workshop proposals which is published annually by BIRS. If you wish your workshop to take place in Granada, you will be able to specify so in your application. However, note that due to the limited availability of the pilot program at IMAG, only a few workshops per year (four or five) will be run at IMAG, so BIRS might select your proposal but suggest you to run it at an alternative site.
