This question resolves to yes if Putin is no longer president of Russia while Zelensky is still president of Ukraine.
For the purposes of this question, the reason for either president to no longer be president is irrelevant: lost election, death, destitution, coup d'état, anything counts. If Putin becomes prime minister while someone else assumes the presidency, Putin will no longer be considered president, even if there is broad agreement that the official president is no more than a figurehead. Ditto for Zelensky.
For the purposes of this question, in the event that either president would lose de facto control over the capital of his country, he would no longer be considered president, regardless of the de jure situation, even if he retreats to some other place and maintains a government in exile of any sort. It's a bit arbitrary, but I think it makes things easier to resolve, as consitutional issues of this type can become very tricky to resolve objectively.
The question resolves as soon as either man is no longer president. If for some reason it happens at exactly the same time for both of them, it resolves as N/A.
Related questions
In case anyone is interested:
https://manifold.markets/AlexandreK/will-russian-forces-take-vuhledar-i
@33cb If Putin is still in control of Moscow and Moscow is still the capital of a country called Russia (be it the federation that it currently is, or some new type of state still called Russia), and Putin is still its president, Putin will still be considered the Russian president.
@AlexandreK if putin is in control of some small non moscow metropolitan area and he calls it Russia (say the other states name themselves after their cities so muscovy etc) or vice versa (putin is in charge of an area called muscovy which includes moscow) this would resolve to putin not being in control?
@yaakovgrunsfeld If Putin is no longer in control of Moscow, this is covered by the clause in the description about losing control over the capital city, so he's no longer president.
If he's president of something that's no longer called Russia, even if it includes Moscow, he's no longer president of Russia either.
This also goes for Zelensky, e.g., if Ukraine loses the war and cedes Kiev to Russia in a peace treaty, but Zelensky is still president, for example from Lviv: this still counts as losing the capital, so he's no longer president of Ukraine. I know this one's a bit weird, but it's for the sake of consistency, and also because I'd rather overspecify the question than underspecify it. Besides, one could argue that Ukraine without Kiev isn't really Ukraine anymore, or that Russia without Moscow isn't really Russia, but it's mainly about removing as much ambiguity as possible.