∂30-SEP-74  1442		1,MG
 I've just noticed that the definition of fact in problem IV on p71.
 of "SUPER LISP"is an application of the Y combinator (λf.((λx.f(xx))(λx.f(xx))))
 If you wanted to discuss Y pehaps that example would be a good place to start?

∂30-SEP-74  0929		1,MG
 Unfortunately I don't know anything non-trivial about modelling data-structures
 The only thing that comes to mind is Rod Burstall's stuff in MI7 (I think !)
 which is about how to represent & reason about pointer manipulating
 algorithms.Although that's a good paper the data-structure models in it
 arn't all that subtle - the nice thing in the paper is an efficient
 formalism (informally presented if I remember right) for asserting facts
 about pointer configurations. I hope to extend my denotational model of LISP
 to include RPLACA,RPLACD etc. but, probably naively, I hadn't thought that
 doing it would raise any hard problems. I guess time will tell!
                           Mike