Could a white belt defeat Jon Jones in a Brazilian jiu-jitsu match?
A step-by-step solution is:
no
A white belt is the lowest ranking in Brazilian jiu-jitsu.

Jon Jones has a purple belt in Brazilian jiu-jitsu under Roberto Alencar.

A purple belt is the second highest ranking in Brazilian jiu-jitsu.

Jon Jones is one of the greatest combat sports athletes to ever live.

.

Thus, the answer is no