Aam Aadmi Party leader Yogendra Yadav on Wednesday said that it is Congress' prerogative to decide what they want to do about government formation in Delhi.Yadav's comments come a day after divisions in Congress came out in open over its support to AAP to form government in Delhi. Addressing the media, Yadav today said that AAP doesn't has any tie-up, alliance or understanding with Congress and it is for the grand old party to decide whether it wants to extend or withdraw support.