This article views the four economies of the South in a long run historical perspective of 1500-2000. It contrasts the history and the initial endowments of the two Northern hemisphere economies China and India which are land scarce and labour abundant with the two Southern hemisphere economies...

According to Euler–Lagrange duality principle of kinematic wave (KW) theory any well-posed initial value traffic flow problem can be solved with the same methods either on the time–space (Euler) plane or the time vs vehicle number (Lagrange) plane. To achieve this symmetry the model...