# Proof Question

• Jan 15th 2008, 11:27 AM
TheMathsDude
Proof Question
http://common.replayers.com/temp/maths1.JPG

Hi guys!

Any help with the above problem would be really greatly appreciated.

Many thanks in advance,

TheMathsDude
• Jan 15th 2008, 12:30 PM
Plato
Here is an example for part c.
$\displaystyle f = \left\{ {\left( {a,1} \right),\left( {b,1} \right),\left( {c,2} \right),\left( {d,2} \right)} \right\},\,A = \{ a,c\} \,\& \,B = \{ b,d\}$
$\displaystyle f\left( A \right)\backslash f\left( B \right) = \emptyset \,\& \,f\left( {A\backslash B} \right) = \left\{ {1,2} \right\}$
• Jan 15th 2008, 02:17 PM
TheMathsDude
Thanks for the help Plato.

Any other help with the other parts would be very helpful!

Many Thanks.
• Jan 15th 2008, 02:44 PM
Plato
Quote:

Originally Posted by TheMathsDude
Any other help with the other parts would be very helpful!

They are just pick-a-points proofs.
Pick a point in the subset; prove it is in the super set.
Comeon, show us some of your own work.