## theEric Group Title Math proof help, please! Relations and subsets involved. I don't see the solution! My math book proved that if sets $A, B,C,D$ existed such that $A \subseteq C$and$B \subseteq D$ then $(A \times B) \subseteq (C \times D)$ I need to show that the converse of that is false. I think the converse is$(A \times B) \subseteq (C \times D)$implies$A \subseteq C$and$B \subseteq D$. But I can't understand how it is false for some group of sets $A,B,C,D$. one year ago one year ago

1. zugzwang Group Title

Use null sets :)

2. theEric Group Title

Alright, thanks.. I never went into writing a proof on that, but I thought about it and didn't see it working... Thank you!

3. zugzwang Group Title

No problem :)

4. theEric Group Title

Ah!! I think I finally see it.. Thanks for making me concentrate more on the null set issue!

5. theEric Group Title

Woo!

6. zugzwang Group Title

Got it? :)