1. Re: 'Unknown' and three-valued logic
--- Rom <kjehas at frisurf.no> wrote:
> |Example case:
> |Simplified rules for unemployments benefits. How to program such
> rules?
> |
> |To qualify for unemployment benefits....
> |1) you must be a national citizen
> |2) you must be unemployed
> |3) you must have earned more than $10000 previous year
> |4) all facts must be documented (if you haven't supplied sufficient
> domentation then employment office cannot make a positive decision)
>
> > All you get is check that the document has been submitted, if yes,
> > then proceed, if no, then send them a leeter asking for more. I don't
> > see anything hard in that. No 3-state needed... I think you have got
> > uninitialised vcars and logic mixed up to much...
>
> Sorry, wrong answer. Even if sufficient documentation is not submitted, they
> cannot say that you are not eligble for benefits.
> The following program produces too many rejections, leading to a row of
> complains......
Ok, fine, but that doesn't mean anything. The above example handles this
perfectly, even though you provided a silly example. First, consider how
you're getting the data. This can tell you whether you've got an unknown.
Check one:
Are you unemployed? Yes [ ] No [ ]
etc.
All you have to do is verify the input (which you should be doing anyways) and
you'll know what extra information you need. Each exception could be added to
a message. ("Need documentation of X. Your income exceeds the limit", etc).
Why is this so hard?
Matt Lewis
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