Took me a while to realise it is based on Scheme and not the Lisps I have used in the past. Did not occur to me to try ~define~ to setq variables!

Also this appears to be more of a set of logic puzzles, right? Going off of the flavour of the second challenge, which is

Define values for cat and dog so that cat and dog are equal? but not eqv?. Furthermore, cdr(cat) and cdr(dog) must be eqv?.

One is assumed to know the difference between equal? and eqv? and the challenge is in coming up with data that satisfies the constraints given.