A strictly monotonic transformation will preserve your preference ordering of states but not your preference ordering for actions to achieve those states. That is, only affine transformations preserve the ordering of expected values of different actions.
Why do you think this restricts to positive affine transformations, rather than any strictly monotonic transformation?
Other monotonic transformations don’t preserve preferences over gambles.
Ah, right, that’s what I was missing. Thanks.
A strictly monotonic transformation will preserve your preference ordering of states but not your preference ordering for actions to achieve those states. That is, only affine transformations preserve the ordering of expected values of different actions.