This is not to be taken too seriously.
Two or three players compete in the solution by relaxations of three linear equations
R1 ≡ a1 x + b1 y + c1 z + d1 = 0,
R2 ≡ a2 x + b2 y + c2 z + d2 = 0,
R3 ≡ a3 x + b3 y + c3 z + d3 = 0.
Before the equations are formed each player adopts one of the residuals Rlt R2, R3 . When there are two players one residual remains unadopted.