(Q1). = Q3, (Q2)w = -(Qi + Q2)/V/2, (Q3)D = (Q2 Q1)//2, (Q4)w = Q4. There are similar relations between the Wigner co-ordinates and our co-ordinates of Fig. 4, d. Wigner states that if the number of particles is a power of 2 and the masses are equal, there is a co-ordinate system of high symmetry in which all particles are treated equally. Unfortunately the form of the potential energy in the c...

A complete classification of the semifield spreads of order q4 that triply-retract to mixed partitions of PG(3, q2) is given.