epiphany

[88888 Dihedral]

Roy Smith於 2013年4月25日星期四UTC+8上午7時50分33秒寫道：
> I discovered something really neat today.
> 
> 
> 
> We've got a system with a bunch of rules.  Each rule is a method which 
> 
> returns True or False.  At some point, we need to know if all the rules 
> 
> are True.  Complicating things, not all the rules are implemented.  
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> Those that are not implemented raise NotImplementedError.
> 
> 
> 
> We used to have some ugly logic which kept track of which rules were 
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> active and only evaluated those.
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> 
> 
> So, here's the neat thing.  It turns out that bool(NotImplemented) 
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> returns True.  By changing the unimplemented rules from raising 
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> NotImplementedError to returning NotImplemented, the whole thing becomes:
> 
> 
> 
>     return all(r() for r in rules)

  Problems of rules in  Boolean algebra or  the bi-level logic
inference engine in AI were all solved long time ago
in the text book about AI.

There are some variations about the multi-level  or 
the continuous level logic engine with some new phases 
in Fuzzy theory  in the expert system.

A dynamical typed language is better to be used in this kind of 
problems.