Joe Dart elected president Y/N
Cory Wong elected president Y/N
A no bet on Joe Dart is not a yes bet on Cory Wong.
It is trivial. Saying NO to a candidate means you're saying YES to ALL other candidates with varying probabilities that would sum to the neg risk of that NO bet.
Perhaps this is pedantic, but this equivalence is ignoring fees, spread, and slippage, right?
If you don't think it's true, then go ahead and arb polymarket for all the incorrect pricing.