Wigner's friend and continuous time evolution of the state of a closed system and the probabilistic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox. The thought experiment posits a friend of Wigner in a laboratory and lets him perform a quantum measurement on a physical system (this could be a spin system or also Schrödinger's cat). This system is assumed to be in a superposition of two distinct states, say, state 0 and state 1 (or "dead" and "alive", in the
Dead or Alive Ultimate of the same color, a copy of "Dead or Alive Ultimate", and some bonus Kasumi-themed extras. In the United States, two trading cards with character pictures on them were randomly included in each game as part of a collector's edition. The game disc of the North American release also contains the Booster Pack for "Dead or Alive 3", which adds numerous character costumes and a new opening cinematic for the game. This disc also included a G4-produced segment from their "Icons" series detailing the history of the "Dead or Alive" series, along with interviews featuring various people from the video