Re: Real world issue:- OT recreational interval

pamelafluente_at_libero.it wrote:
> Marshall ha scritto:
>
> > > A binary function f(x,y) is called idempotent if for all x
> > >
> > > f(x,x) = x
> >
> > Yes, this is exactly what I've been saying, and what's been
> >
> > You still don't understand how binary functions are used
> > In it, I said "If the binary form of the aggregate
> > function is idempotent, the aggregate will return the same value
> > even if values are repeated arbitrarily. Since + is not idempotent,
> > sum() is "sensitive" to repeated values. Since binary min *is*
> > idempotent, aggregate min() is not "sensitive" to repeated
> > values."
> >
>
>
> Marshall,
>
> Your statement
>
> "If the binary form of the aggregate
> function is idempotent, the aggregate will return the same value
> even if values are repeated arbitrarily. Since + is not idempotent,
> sum() is "sensitive" to repeated values. Since binary min *is*
> idempotent, aggregate min() is not "sensitive" to repeated
> values."
>
> is TRUE. I already told you 40 posts ago. .
>
> what it states is formally:
>
> idempotent => "Not replication sensitive"
>
> This is true. What I am stating is that
>
> "Not replication sensitive" => "binary idempotent"
>
> is a false statement.
>
> In fact:
>
> 1. Count Distinct is "Not Replication sensitive" but also
> 2 Count Distinct is not binary Idempotent
> e.g. countDistinct (5,5) = 1 => Count distinct is not binary
> idempotent
>
> so it is NOT true that
>
> "Not replication sensitive" => "idempotent"
>
>
> Therefore
>
> binary idempotent <=> "Not replication sensitive"
>
> does not hold.
>
> If it does not hold for the binary case (n=2), it does not hold in
> general.
>
> This is elementary logic. I have started from the definition.
>
> This is not philosophy. Please use logic/math argument to respond.
> Do not just say that I do not understand. That's not a logic argument.
>
> If my argument has a flaw, please, Marshall or Bob or anyone, point out
> * exacly where it is * so that I can see it.
>

The flaw is simple. Marshall was talking about the binary forms of aggregate functions. Count Distinct (a,b) is not the binary form of the aggregate Count Distinct (S).

> I am not afraid to recognize it.

If it's not fear, then what is it? Pride? Lack of intelligence?

>
> -P
>
> > Marshall
Received on Mon Sep 18 2006 - 20:14:42 CEST