! SEND_MORE.txt - axioms for SEND+MORE=MONEY problem

!/
  Problem to solve:

       S E N D
     + M O R E
     ---------
     M O N E Y

  where
    each different letter is a different digit 0 ... 9
    which combine to form 4- and 5- digit decimal numbers
    first digits S and M are not 0
  We find the letter->digit mapping that makes the equation correct.
!\

! top-level axiom for generating solution as a valid expression

  (solution: $eqn)<
    (== ($eqn) (%S %E %N %D + %M %O %R %E = %M %O %N %E %Y)),
    (different- digit (%S %E %N %D %M %O %R %Y)),  ! distinct 1-digit symbols
    (/= %S 0), (/= %M 0),
    (equation ($eqn)).        ! instantiated equation must be satisfied
      ! -- note that grammar merges adjacent digits to form number

! -- See /util directory for axioms for utility predicates.