out <= 
  (          not b and     c and not d ) or
  (    a           and     c and not d ) or
  (    a and     b and     c           ) or
  (              b           and     d ) or
  (not a and not b           and not d );

out = 
  (     ~b &  c & ~d ) |
  ( a      &  c & ~d ) |
  ( a &  b &  c      ) |
  (      b      &  d ) |
  (~a & ~b      & ~d );