[wcrossbow]

Just rename a to b and b to a.

[nuancebydefault]

Is that allowed? You will prove another equation. You cannot swap pi and e either.

[Ma8ee]

You are not swapping the values, you are swapping the names.

[kelnos]

pi and e aren't names; they're values. Of course you can't swap values.

[kleiba]

Why the downvote? That's a correct argument.

[supernewton]

It is not. a and b are not symmetric in this equation, you can't just swap them.