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Re: Preconditions /effects vs Preconditions/Postconditions

From: Jeff Lansing <jeff@polexis.com>
Date: Mon, 15 Sep 2003 13:13:00 -0700
Message-ID: <3F661D4C.4060303@polexis.com>
Cc: www-ws@w3.org

Walden Mathews wrote:

>How about this:
>
>The post-condition of a (successful) credit card transaction
>is that your loan balance is increased and your available credit
>is decreased, both by the transaction amount.
>
>  
>
If post-conditions are conditions, then there are 2 post-conditions 
here, which could be stated as:

1) the increase in the loan balance is equal to the transaction amount
2) the decrease in the available credit is equal to the transaction amount.

(and which could be conjoined into a single post-condition, if you prefer).

There are also two effects:

a) the loan balance has been increased (by the transaction amount, as it 
happens)
b) the available credit has been decreased (also by the transaction 
amount, as it happens).

Jeff
Received on Monday, 15 September 2003 16:15:38 GMT

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