Explore

• Function scheme/tautology?
  

  Search truth tables for the absence of FALSE to identify tautologies.

  Builds on scheme/truth-table.

  <<scheme/truth-table>>
  
  (define (tautology? procedure arity)
    (not (member #f (map (lambda (row)
                           (car (reverse row)))
                         (truth-table procedure arity)))))
  

  <<scheme/tautology?>>
  
  (unless (tautology? (lambda (p) (or p #t)) 1) (raise #f))
  (unless (tautology? (lambda (p q) (or p q #t)) 2) (raise #f))
  (unless (tautology? (lambda (p q r) (or p q r #t)) 3) (raise #f))
  
  (when (tautology? (lambda (p) (or p)) 1) (raise #f))
  (when (tautology? (lambda (p q) (or p q)) 2) (raise #f))
  (when (tautology? (lambda (p q r) (or p q r)) 3) (raise #f))
  
  "tests passed"
  

  tests passed