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Fix for +-rule-down #15

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Fix for +-rule-down #15

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6 changes: 5 additions & 1 deletion screamer.lisp
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Original file line number Diff line number Diff line change
Expand Up @@ -4205,13 +4205,17 @@ Otherwise returns the value of X."
(fail))))

(defun +-rule-down (z x y)
;; ORIGINAL COMMENT
;; note: We can't assert that X and Y are integers when Z is an integer since
;; Z may be an integer when X and Y are Gaussian integers. But we can
;; make such an assertion if either X or Y is real. If the Screamer
;; type system could distinguish Gaussian integers from other complex
;; numbers we could make such an assertion whenever either X or Y was
;; not a Gaussian integer.
(if (and (variable-integer? z) (or (variable-real? x) (variable-real? y)))
;; FIX: 2013/02/25 The argument above must surely be incorrect. If Z is an integer, and Y is a real say 2.5
;; then X will surely not be an integer. The argument *does* work if either X or Y
;; is an integer
(if (and (variable-integer? z) (or (variable-integer? x) (variable-integer? y))) ; Original: (or (variable-real? x) (variable-real? y)))
(restrict-integer! x))
;; note: Ditto.
(if (and (variable-real? z) (or (variable-real? x) (variable-real? y)))
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