# Relational Notation - Domain and Range restriction help required

• Dec 5th 2013, 12:07 PM
misheck
Relational Notation - Domain and Range restriction help required
I have a question from an exercise that I am struggling with or to get grips with. I have to write all of them in relational notation in terms of drives etc etc. Sorry I cannot post my solutions to the other questions to show you exactly what I am trying to achieve. Here is the question, I have been presented with drives: PERSON <-> CARS. I have been asked to list the people who drive BMW but not VW. I have also been asked to list the other cars (ie not including VW) driven by the people who drive a VW.

For list the people who drive BMW but not VW if I put a range restriction to show those that drive BMW I could also have a list of people that drive BMW and VW and that would not work and I cannot have a range restriction and an additional range restriction. I am trying to avoid having in my list people that drive both BMW and VW.

For the list the other cars (ie not including VW) driven by the people who drive a VW, I am not sure how to go about solving this besides have a range restriction inside another range restriction.
• Dec 5th 2013, 05:32 PM
chiro
Re: Relational Notation - Domain and Range restriction help required
Hey misheck.

Can you please specify the specific set definitions for persons and cars? Also if you have any specific definition of the relation (even if its partial) please point that out as well.
• Dec 5th 2013, 10:27 PM
misheck
Re: Relational Notation - Domain and Range restriction help required
Quote:

Originally Posted by chiro
Hey misheck.

Can you please specify the specific set definitions for persons and cars? Also if you have any specific definition of the relation (even if its partial) please point that out as well.

Hi Chiro, there is not much that has been given to work with but I have attached a picture of the questionto help. If you can also guide me in the right direction on where I can get more information on the topic I will be very grateful.

Attachment 29863
• Dec 6th 2013, 02:51 PM
chiro
Re: Relational Notation - Domain and Range restriction help required
Hint: In terms of set theory you exclude objects using the set difference. In this case considers Persons \ {Albert,Victoria}
• Dec 7th 2013, 09:43 AM
misheck
Re: Relational Notation - Domain and Range restriction help required
thanks for the hint, I will do a bit more reading.