How to use of upcase_atom/2 to get uppercase letters in an output

I just tested the proof of Pelletier problem 17 with swipl simple_server.pl and it works, Firefox provides the proof and one can read on the terminal:

% 54,890,488 inferences, 4.423 CPU in 4.424 seconds (100% CPU, 12409457 Lips)

Security worries apart, that would be a good solution for Prolog provers online.