Comment Feed for Channel 9 - The Verification Corner: Loop Invariants http://ecn.channel9.msdn.com/o9/ch9/3/5/4/9/1/5/vcloopinvariants_512_ch9.png Channel 9 - The Verification Corner: Loop Invariants In this episode of The Verification Corner, Rustan Leino talks about Loop Invariants.  He gives a brief summary of the theoretical foundations and shows how a program can sometimes be systematically constructed from its specifications.  Rustan Leino is a Principal Researcher in the Research in Software Engineering (RiSE) group at Microsoft Research. Try Spec# in your web browser at http://rise4fun.com/specsharp! Whiteboard slides [.pdf] [.pptx]  Spec# Demo project [.zip]Find past and future episodes of the The Verification Corner! The Verification Corner is a show on Software Verification Techniques and Tools. The show is produced by the Research in Software Engineering team (RiSE) coordinates Microsoft's research in Software Engineering in Redmond, USA. en Fri, 24 May 2013 07:29:23 GMT Fri, 24 May 2013 07:29:23 GMT Rev9 Re: The Verification Corner: Loop Invariants Very interesting video, thx

posted by Flynn0r

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989249580000000 Tue, 12 Jan 2010 20:29:18 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989249580000000 Flynn0r Re: The Verification Corner: Loop Invariants I agree, I'd like to see a lot more videos in this series. Also, that is a way cool digital whiteboard - I've always wanted a whiteboard I could print from. It does make me wonder what other "toys" MSR use as part of their working day.

posted by tomkirbygreen

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989508480000000 Wed, 13 Jan 2010 03:40:48 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989508480000000 tomkirbygreen Re: The Verification Corner: Loop Invariants More videos are coming, The Verification Corner will cover all the aspects of software verification. At MSR, we usually rely on regular whiteboards like everyone else Smiley In the movie, we've used an eBeam system to capture the pen to give a better video experience.

 

posted by peli

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989535580000000 Wed, 13 Jan 2010 04:25:58 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989535580000000 peli Re: The Verification Corner: Loop Invariants Very nice.

 

I only wish there was an invariant of having the video released closer to the creation. Wink

posted by N2Cheval

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989797710000000 Wed, 13 Jan 2010 11:42:51 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989797710000000 N2Cheval Re: The Verification Corner: Loop Invariants > video released closer to the creation

 

Note sure I get it. Do you mean the video should be on the Spec# web site?

posted by peli

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989933890000000 Wed, 13 Jan 2010 15:29:49 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c633989933890000000 peli Re: The Verification Corner: Loop Invariants Very good explanation of the subject! And the tools show to really help in the process.

 

Could the same thing be accomplished with CodeContracts? Or is Spec# further in its evolution? I was wondering because CodeContracts is what most people will be using (I guess) so it would make more sense to show the example in CodeContract instead of Spec#.

posted by Djeez

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634000518790000000 Mon, 25 Jan 2010 21:31:19 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634000518790000000 Djeez Re: The Verification Corner: Loop Invariants Thanks!

 

CodeContracts could in principle be used to do the same thing.  However, we have more engineering to do for CodeContracts to support this particular example.  While CodeContracts does support pre- and postconditions, it has no direct support for writing loop invariants, which play a central role in this episode of Verification Corner.  As a more technical point, the static-checking tools for CodeContracts don't have the support for non-linear arithmetic (that is, multiplication of a variable with itself or with another variable) that is required to reason about the computation of cubes.

 

For now, the best you can do in CodeContracts is to use an Assert just inside the loop body to express the loop invariant and then rely on run-time checking.  Still, you may find that doing that improves your ability to reason about what's going on in the loop.

posted by leino

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634001517280000000 Wed, 27 Jan 2010 01:15:28 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634001517280000000 leino Re: The Verification Corner: Loop Invariants I suppose you're referring to the mention of "it is December" in the video, while it was actually released here in January.  But you can make wishes any time of year. Smiley

posted by leino

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634001519670000000 Wed, 27 Jan 2010 01:19:27 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634001519670000000 leino Re: The Verification Corner: Loop Invariants Hi all, I have a rather basic question. Why Hoare's triple is written as {P}S{Q}, instead of P{S}Q? Is there any special reason behind it?

posted by Hongyi

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634020569460000000 Thu, 18 Feb 2010 02:29:06 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634020569460000000 Hongyi Re: The Verification Corner: Loop Invariants In Tony Hoare's classic 1969 paper, the triples were written P{S}Q.  Sometime later (I'm not sure when), the common notation switched to {P}S{Q}.  I think (but I'm not certain) that the reason for the switch was to make the assertions P and Q look as if they were comments, like in the syntax of the Pascal programming language.

posted by leino

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634034256850000000 Fri, 05 Mar 2010 22:41:25 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634034256850000000 leino Re: The Verification Corner: Loop Invariants Can the system handle overflow (e.g. if the array of cubes is so large that the cubes of higher indices exceed the maximum integer value)?

posted by softwarekev

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634085094610000000 Mon, 03 May 2010 18:51:01 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634085094610000000 softwarekev Re: The Verification Corner: Loop Invariants No, the Spec# verifier ignores issues of overflow.  Checks for arithmetic overflow can be added to the verifier, at the cost of additional specification overhead for users.  In some other languages we use for verification, like Dafny, the integers are unbounded, so there will never be any overflows.

posted by leino

]]> http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634219241390000000 Wed, 06 Oct 2010 01:08:59 GMT http://channel9.msdn.com/Blogs/Peli/The-Verification-Corner-Loop-Invariants#c634219241390000000 leino