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NNTP-Posting-Date: Sat, 15 Jan 2011 11:39:32 -0600
Date: Sat, 15 Jan 2011 12:39:15 -0500
From: "Peter C. Chapin" <PChapin@vtc.vsc.edu>
Organization: Vermont Technical College
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Subject: Question about round__ proof function in SPARK proofs.
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Date: 2011-01-15T12:39:15-05:00
List-Id: <comp.lang.ada>

I'm trying to discharge a VC in a SPARK proof. After simplification I
have just:

H1: julian_date >= 4830771 / 2 .
H2: julian_date <= 2489665 .

The conclusions are:

C1: round__(julian_date + 1 / 2) >= - 2147483648 .
C2: round__(julian_date + 1 / 2) <= 2147483647 .

This VC is the result of a type conversion from a floating point type to
an integer type. It seems evident that the conclusions are true for any
reasonable definition of round__. I assume the simplifier is not proving
this VC because it doesn't have any built-in knowledge of the proof
function round__, even though it was inserted automatically be the
examiner. So I think maybe I'm supposed to specify the properties of
round__ somewhere. Am I on track here?

Thanks in advance for any insights you might have.

Peter