(s1 or s2 or s3 or s5 or s6) and
not (s1 and s2) and not (s1 and s3) and not (s1 and s4) and
not (s1 and s5) and not (s1 and s6) and not (s2 and s3) and
not (s2 and s4) and not (s2 and s5) and not (s2 and s6) and
not (s3 and s4) and not (s3 and s5) and not (s3 and s6) and
not (s4 and s5) and not (s4 and s6) and not (s5 and s6).
I think you mean to add “or s4” on the first line:
(s1 or s2 or s3 or s4 s5 or s6) and
not (s1 and s2) and not (s1 and s3) and not (s1 and s4) and
not (s1 and s5) and not (s1 and s6) and not (s2 and s3) and
not (s2 and s4) and not (s2 and s5) and not (s2 and s6) and
not (s3 and s4) and not (s3 and s5) and not (s3 and s6) and
not (s4 and s5) and not (s4 and s6) and not (s5 and s6).
Seems to be a typo here:
(s1 or s2 or s3 or s5 or s6) and not (s1 and s2) and not (s1 and s3) and not (s1 and s4) and not (s1 and s5) and not (s1 and s6) and not (s2 and s3) and not (s2 and s4) and not (s2 and s5) and not (s2 and s6) and not (s3 and s4) and not (s3 and s5) and not (s3 and s6) and not (s4 and s5) and not (s4 and s6) and not (s5 and s6).
I think you mean to add “or s4” on the first line:
(s1 or s2 or s3 or s4 s5 or s6) and not (s1 and s2) and not (s1 and s3) and not (s1 and s4) and not (s1 and s5) and not (s1 and s6) and not (s2 and s3) and not (s2 and s4) and not (s2 and s5) and not (s2 and s6) and not (s3 and s4) and not (s3 and s5) and not (s3 and s6) and not (s4 and s5) and not (s4 and s6) and not (s5 and s6).