∂04-FEB-75  1137		1,MG
 Subject: Future meetings of Program Reasoning Group. 
 
 The next meeting is  in the conference room at Stanford  A.I. Lab. at
 3.30  p.m.  on mon.  17 feb. Balint Domolki  (who's visiting the  A.I.
 Lab. from Hungary) will talk. 
 
 The meeting following that will be at Xerox PARC at 3.30 p.m. on mon.
 3 march.  Richard Waldinger will talk. 
 
 The debate described in previous  messages (which was conceived of by
 Bob.  Boyer)  is  to be  organanised  by  Richard  Waldinger. Further
 suggestions concerning it should be sent to Richard at SRI. 
 
 Sorry about the  vast list of names  that non-SU-AI people have  been
 getting at  the top of  previous messages -  I had no  idea they were
 appearing!  I hope I've now found the right hack to suppress them. 
 
 If you would  like to  stop getting these  messages, or  if you  know
 someone who'd like to start getting them, please let me know. 
 
 Mike


∂29-JAN-75  1350		1,MG
 How'd you like to air your prejudices to the RAP group fairly soon?
 The current schedule is J Moore next time, then Richard Waldinger, then
 hopefully you?????.
 
 Mike

∂29-JAN-75  1133		1,MG
 Subject: Next Meeting of Program Reasoning Group
 
 The next meeting is on  mon. feb. 3 at 3:30 p.m. in  SRI's I Building
 in room s109 (the keidanren). 
 
 J  Moore will  discuss his  recent work on  the celebrated  pure LISP
 theorem prover. 
 
 J suggests that peoplee unfamiliar with the Boyer/Moore  prover might
 like to go  to Bob Boyer's talk on  fri.  jan. 31 at  1:30 in SU-AI's
 conference room.  (This talk is the first of the Waldinger/Green AP. 
 seminars)
 
 It's been suggested that  it might be fun  to have a debate  in which
 people defend views OPPOSITE  to what they hold.The topic that's been
 suggested is  the relative  merits of  low level  languages (such  as
 INTERLISP) vs.  those of high  level ones  (like QLISP). Does  anyone
 have any  more suggestions or have a  particular hate they would like
 to defend (not nec. one of those above) ? 
 
 Mike. 


∂10-JAN-75  1635		1,MG
                     A DEFENCE OF ORDINARY LANGUAGES.
 
 Why bother to try and model the semantics of messy real languages - wouldn't
 it be better to concentrate effort on sensible well designed ones? 
 Several people have told me something like this on hearing that I was trying 
 to handle LISP (warts and all).
 Here's my defence reaction:
 
 (1)Different people dislike different aspects of LISP. John McCarthy thinks that
    call-by-value is wrong (since the analysis of recursion in terms of fixed points
    is slightly simpler if call-by-name is used). People at the Programming
    Research Group in Oxford object to LISP's fluid variables. John Allen doesn't
    like RPLACA,RPLACD and would prefer less general (but more structured)
    data-structure primitives.
 
 (2)I don't think one can allways tell whether a particular feature poses problems
    until one has tried hard to model it. For example early claims that
    call-by-value ruled out the valid use of computation-induction have been
    refuted by DeRoever et.al. of Amsterdam.
 
 (3)People actually program in nasty languages and so if one wants to get reasoning
    techniques realistically tested then it helps to make them applicable to real
    problems.
 
 (4)Working only with abstract toy languages opens the door to the danger that
    one will miss genuine problems which arise in practice but not in theory.