No. Accepting this gift would impair your objectivity in your relationship with the supplier. This would constitute a conflict of interest and might prevent you from taking decisions that are in the best interest of CERN. You should politely decline the offer and, if necessary, refer the supplier to the relevant dispositions of the Code of Conduct.
[EN] I am responsible for the management of a contract with a supplier who has offered me two tickets for a professional tennis match. May I accept these tickets?