A parody of the three laws of thermodynamics in terms of a person playing a game: (1) you can't win; (2) you can't break even; (3) you can't even get out of the game.

(physics) Any theorem stating that a particular situation is not physically possible.

(mathematics) A theorem used to confirm the limit of a function via comparison with two other functions whose limits are known or easily computed.

A theorem stating that the interaction picture does not exist in an interacting, relativistic quantum field theory.

(physics) A no-go theorem stating that, during measurement of an entangled quantum state, it is not possible for one observer, making a measurement of a subsystem of the total state, to communicate information to another observer.

(mathematics) A theorem about discrete dynamical systems. One of its implications is that if a discrete dynamical system on the real line has a periodic point of period 3, then it must have periodic points of every other period.

A mathematical theorem, important for quantum logic, proving that the Born rule for the probability of obtaining specific results for a given measurement follows naturally from the structure formed by the lattice of events in a real or complex Hilbert space.

(geometry) A theorem asserting that every valuation on convex bodies in Rⁿ that is continuous and invariant under rigid motions of Rⁿ is a linear combination of the quermassintegrals (or, equivalently, of the intrinsic volumes).

(group theory) A theorem which proves that, given a mind swap machine that can't be used on the same pair of people more than once, it is possible to reverse any number of mind swaps by introducing two more people that did not have their minds swapped with anyone before.

(graph theory) The theorem stating that every cubic bridgeless graph contains a perfect matching.