ISTANBUL Istanbul University has officially served the city’s mayor, Ekrem İmamoğlu , with a notice annulling his university diploma — nearly 55 days after publicly announcing the decision, local media announced on May 13. The delayed notification opens the door to challenge the ruling through legal avenues for İmamoğlu, who has been imprisoned since late March on the charge of corruption. "Due to your irregular transfer, a decision has been rendered to revoke both the transfer and, by