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• Bitops/signed-byte-p

Signed-byte-p-of-decrement-when-natural-signed-byte-p

Decrementing a positive N-bit signed creates an N-bit signed.

Definitions and Theorems

Theorem: signed-byte-p-of-decrement-when-natural-signed-byte-p

(defthm signed-byte-p-of-decrement-when-natural-signed-byte-p
  (implies (and (signed-byte-p n x) (<= 0 x))
           (signed-byte-p n (1- x))))