Israel claims that Hamas has a command center under al-Shifa Hospital in Gaza City. Hamas denies this. This market will settle as YES if credible reporting confirms the existence of a command center underneath the hospital or in its immediate vicinity, in addition to the claims Israel has provided as of November 10, 2023. The market will expire on June 30, 2024. If no evidence emerges by that time, or it is shown that there is no such command center, this market will settle as NO. 

Update, November 19, 8:46 AM PST: The term "no evidence" in the original question was meant to be relative, not absolute. This market will resolve YES if there is enough evidence to conclude there was a command center, but not otherwise. If I estimate there was at least a 90% chance that Hamas had a command center under al-Shifa this market will resolve as YES based on a totality of the evidence. The evidence will be judged based on a consensus of credible reporting, mainly taken from The New York Times, the Wall Street Journal, The Economist, and The Washington Post. If before the end date it becomes 90% likely there was no command center in my judgment, this market will resolve as NO. If we get to the end of the market and it's not 90% certain in either direction, the market will resolve as NO. 

As for definitions, a "command center" is a place where Hamas either plans or gives orders for military operations. It does not have to be the main command center of its entire war effort, or necessarily a "headquarters." The command center must have been in use as a command center at some point during the current war or during the events immediately preceding it. 