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From: Gerald Britton <gerald.britton@gmail.com>
Newsgroups: comp.lang.python
Subject: re: Operator Precedence/Boolean Logic
Date: Sat, 16 Jul 2016 09:58:31 -0400
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>Earlier you said:

>* > 1. Graphs -- the kind mathematicians define with "Let G =3D(V,E) be a
*>* > graph..."
*>  >* I would make the empty graph (zero nodes) falsey, and non-empty
graphs (one
*>* or more nodes) truthy.
*>  >  >* > 2. Automata which in a way are special kinds of graphs
*>  >* As above.
*

>Now you say:

>* > If on the other hand you are giving that =E2=80=9Creturn True=E2=80=9D=
as a serious useful
*>* > definition?
*>  >* Sure. An automata is an object, and by default, all objects are
"something"
*>* and hence truthy. That's the "no-brainer" answer, it requires no
*>* justification at all. If you think the answer should be something else,
*>* *that* is what needs justification. Why shouldn't it be truthy?
*

>How do we put these two together>


easy peasy:  lists, tuples, dicts etc are also objects.  They define
their truthiness by the presence of members.  An empty list has a
boolean value of false.

for a custom object, you can accept the default boolean value of true
or override __bool__ so that it returns what you want.  So for a graph
G, I'd say if |V| =3D |E| =3D 0, G has a boolean value of false.

Maybe thusly?https://en.wikibooks.org/wiki/Sufism/Nasrudin#Of_any_two_optio=
ns_choose_the_third

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Gerald Britton, MCSE-DP, MVP
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