@WillowChem The problem is {x:P(x)} was how they defined sets, so once you say "this is an illegitimate way to define sets" you need to solve that problem - new set theory was one solution
We can see the PnL difference:
Long 2 units of Harris ECV would have made 2x(267-260) = 14
Long 1 unit of Harris ECV supremacy would have made (22-(-1)) = 23
Spreads should depend on vol, not on the size of the number!
Harris/Trump ECV is 8 wide.
Harris - Trump ECV is 6 wide.
Harris - Trump is *exactly* 2x Harris ECV in risk terms. The market is equivalent to Harris being 3 wide.