while loop - multiple condition

Rustom Mody rustompmody at gmail.com
Mon Oct 13 18:26:57 CEST 2014


On Monday, October 13, 2014 9:43:03 PM UTC+5:30, Rob Gaddi wrote:
> On Mon, 13 Oct 2014 09:56:02 +1100
> Steven D'Aprano  wrote:
> > When you have multiple clauses in the condition, it's easier to reason about
> > them if you write the clauses as positive statements rather than negative
> > statements, that is, "something is true" rather than "something is not
> > true", and then use `not` to reverse it if you want to loop *until* the
> > overall condition is true.

> I was just explaining this concept to a young pup the other day.  De
> Morgan's lets you say that (not (p and q)) == ((not p) or (not q)), but
> the positive logic flavor is substantially less error-prone.  People
> are fundamentally not as good at thinking about inverted logic.

Curious: Which of

- (not (p and q))
- ((not p) or (not q))

is more positive (less negative)??



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