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
Kasumi (Dead or Alive) sneak behind them and attack from the rear, or just confuse them mightily." IGN described her "a great character for any level of player" of "Dead or Alive 2" as "novices will certainly enjoy her easy mechanics, while master players will find some of the most evil combinations in the game with Kasumi." According to Andrew Alfonso's GameSpy guide to "Dead or Alive Ultimate", Kasumi's key moves include high kicks and a cartwheel attack, which is perfect against low attackers. Kasumi's preferred and recommended tag team partner is Ryu Hayabusa. GameSpy's Chau wrote that in "DOA3", "Kasumi's got some very