the minimax theorem says: in zero-sum games, there's a saddle point strategy

Zero-sum game

Zero-sum game: one player's gain equals another's loss

the optional stopping theorem says about martingales and stopping times

The optional stopping theorem states that for a martingale, stopping at a stopping time with finite expectation preserves the martingale property

non-convex loss landscapes are hard: many local minima and saddle points

Non-convex loss landscapes are hard due to many local minima and saddle points

Convex optimization

Convex functions have only one global minimum

Invertible matrix

Rank-nullity theorem: rank(A) + nullity(A) = n

a dominant strategy is: optimal regardless of what other players do

A dominant strategy maximizes payoff irrespective of opponents' actions