# Re: WWW/Internet 2009: 2nd CFP until 21 September

Date: Fri, 14 Aug 2009 11:34:53 -0300
Message-ID: <4a85760d\$0\$23780\$9a566e8b_at_news.aliant.net>

paul c wrote:

```> Mr. Scott wrote:
> ...
>
```

>> The table {X,A,B,C,D,E} has one predicate. All of the attributes
>> apply to all orders even if their values are at present unknown.
>>
>> The predicate is "being an order that has order number X for customer
>> E that was placed on date D with delivery e-mail address A and
>> delivery snail-mail address B and delivery contact phone number C
>> where X is an element of the domain of all order numbers and E is an
>> element of the domain of all customers and D is an element of the
>> domain of all dates and A is an element of the domain of all e-mail
>> addresses and B is an element of the domain of all snail-mail
>> addresses and C is an element of the domain of all phone numbers"
>> where X, A, B, C, D and E are free. A row in the table consists of
>> values that are to be substituted for free variables in the
>> predicate. The row {x1,a1,b1,c1,d1,e1} would mean after substitution
>> "the order with order number x1 for customer e1 that was placed on
>> date d1 with delivery e-mail address a1 and snail-mail address b1 and
>> delivery contact phone number c1." A row with a null snail-mail
>> address and a null delivery contact, {x2,a2,d2,e2} means after
>> substitution "the order that has order number x2 for customer e2 that
>> was placed on date d2 with delivery e-mail address a2 and delivery
>> snail-mail address B and delivery contact phone number C where B is an
>> element of the domain of all snail-mail addresses and C is an element
>> of the domain of all phone numbers."
>> ...
>
> How can four values be substituted into a predicate with six place-holders?

It will be interesting to see the answer. Ordinarily, doing so would more-or-less make a new predicate with 2 free variables. Received on Fri Aug 14 2009 - 16:34:53 CEST

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