Thanks Chris for your answer.
I will be patient and I will wait the new release 4.2 concerning this specific question.
I see that boolean algebra is difficult to handle with maxima. poly_solve is very practical for many stuffs, for logic I am a bit puzzled using it.
I did some truth tables and conjonted normal forms with this library :
https://github.com/andrejv/maxima/blob/master/share/logic/logic.mac
that I considered very useful but we already talk about its integration which needs some works.
Further elements about the initial question, I noticed this behavior:
(in1) prederror:true$
(in2) debugmode(true)$
(in3) x=0;
(out) x=0
(in4) y>0;
(out) y>0
(in5) x=0 or y>0;
(out) Unable to evaluate predicate y > 0I will be happy to share with you on these features when the new release will be available.