A very interesting problem. I could not find a solution with 3 cars. Have you ever seen a proof or any argument why 4 are necessary?
In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.
No I haven't.
But I have been thinking how to rescue the empty cars.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman
Only one question. It doesn't says that you will be able to tow another car! Even if you can. It will use more patrol that's wouldn't take you to quarter a desert per car!
Creeper_mode - Amateur Math solver
Love Logic Puzzles.