@FredrikEisele : why do you need the negative numbers? Also, the first question ask “what is this as a preorder?”; I understood this to require an interpretation of what \\(Cost^{op}\\) is, what it can represent - and I cannot figure this out: to me it seems just the same thing as \\(Cost\\) except that it tells you which things are cheaper rather than which ones are more expensive. Any hint? Thanks!