Thanks, Henry. Yes… it's all very much not obvious to me too.
I was going to mention NuVoc: http://code.jsoftware.com/wiki/Vocabulary/ampdot — but I felt ignorance would suit me better. How to present theorems (propositions?) in J would be good to standardize. How to prove them (run them?) even better. Right now I'm writing test scripts and I'm bog-eyed with typing out assert (".phrase) -: (result) over and over again in multifarious forms from an extensive session log. Every six months I devise a new solution to this perpetual problem – and six months later I reckon it's a dog! Until that's sorted, I can't pretend to myself J does math. J does calculations. Ian On Sat, Jun 16, 2018 at 3:35 AM, Henry Rich <henryhr...@gmail.com> wrote: > It's a theorem: > > [x] >@(f each) y > > [x] >@(f&.>) y > > [x] >@((<@:f)&>) y > > [x] (>@(<@:f)&> y > > [x] (>@:<)@:f&> y > > [x] f&> y > > [x] (f every) y > > > Some of these steps are very much not obvious IMO. And you have to get > the rank of each right, that is, use the NuVoc definition of &. rather than > the Dictionary one. > > Henry Rich > > > On 6/15/2018 8:30 PM, Ian Clark wrote: > >> I've checked Chapter 1 off, but that's only to say I've checked out the >> code and verified it gives the results claimed. I didn't see it as my job >> to rewrite the treatment to make it clearer – which I can't do anyway >> without being sure what the author is trying to convey. >> >> I must confess that first section completely baffles me. I cannot see how >> to relate the "general rule" to actual examples of J code, although the >> article goes on to do just that … it seems. Does the "rule" represent real >> working J code? – even in a generic sense? Is it even true? (Theorems have >> to be true, but rules only have to be obeyed.) If it isn't always true, am >> I to understand it as a rule-of-thumb?And if it is in fact universally >> true, what procedure must I, the novice reader, follow in order to convert >> the "generics" into "specifics" to verify the fact? >> >> I'd be grateful for someone to cast light on the matter. Failing which, >> maybe I ought to remove my green checkmark, stand aside to let someone >> else >> scratch their head over it. >> >> On Sat, Jun 16, 2018 at 12:41 AM, David Lambert <b49p23t...@gmail.com> >> wrote: >> >> 50 Shades of j chapter 1 now says that rule is completely general. I'm >>> somewhat weak on j transformations and proofs, although what was there >>> was >>> incorrect because of a counterexample: >>> >>> >>> every=.&> NB. uses compose >>> each=.&.> NB. uses under >>> rule =: (f every) -: >@(f each) >>> >>> NB. Is completely general? >>> >>> >>> thank you, Dave >>> >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > > > --- > This email has been checked for viruses by AVG. > https://www.avg.com > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
