*To*: Makarius <makarius at sketis.net>*Subject*: Re: [isabelle] Rational numbers in Isabelle/ML*From*: Manuel Eberl <eberlm at in.tum.de>*Date*: Sun, 3 Apr 2016 15:53:20 +0200*Cc*: cl-isabelle-users at lists.cam.ac.uk*In-reply-to*: <alpine.LNX.2.00.1604031353330.27940@lxbroy10.informatik.tu-muenchen.de>*References*: <56FEEB91.9060000@in.tum.de> <alpine.LNX.2.00.1604012351350.35180@lxbroy10.informatik.tu-muenchen.de> <56FFBBEF.1060602@in.tum.de> <alpine.LNX.2.00.1604022342050.55508@lxbroy10.informatik.tu-muenchen.de> <57004746.6080409@in.tum.de> <alpine.LNX.2.00.1604031353330.27940@lxbroy10.informatik.tu-muenchen.de>*User-agent*: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1

Manuel On 03/04/16 14:01, Makarius wrote:

On Sun, 3 Apr 2016, Manuel Eberl wrote:* Rat.inv and MyRat.inv look odd to me, but for differentreasons. Arethese actually correct?There is a ~ missing in MyRat.inv. That code should definitelyreceive a thorough review before it goes anywhere. Rat.inv looks fineto me.How about a formally specified and verified implementation? Itshould bemostly trivial with all the algebraic tools in Isabelle/HOL.However, I would imagine that the exported could would be quite ugly.I did not mean to use exported code, but just to make a demo theorywith all the definitions and maybe some simple proofs (e.g. inHOL/ex). The idea is just to make certain intentions and invariantsexplicit, notably the sign of certain parts.A related question is about sign in lcm/gcd: in structure Integer,PolyML.IntInf, and the HOL definitions. There is also a connection ofPolyML.IntInf operations with the code generator in AFP Gauss_Jordanand Echelon_Form.Makarius

**References**:**[isabelle] Rational numbers in Isabelle/ML***From:*Manuel Eberl

**Re: [isabelle] Rational numbers in Isabelle/ML***From:*Makarius

**Re: [isabelle] Rational numbers in Isabelle/ML***From:*Manuel Eberl

**Re: [isabelle] Rational numbers in Isabelle/ML***From:*Makarius

**Re: [isabelle] Rational numbers in Isabelle/ML***From:*Manuel Eberl

**Re: [isabelle] Rational numbers in Isabelle/ML***From:*Makarius

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