CS476 Program Verification

Spring 2019

Time: Tuesday and Thursday, 9:30-10:45

Place: Siebel Center 1131

Professor: José Meseguer

Office Hours: Immediately following class in Dr. Meseguer's office.


Reading Materials


Grading

The course will consist of weekly homework assignments and one long homework assignment towards the end covering a wide range of the course material. Each problem on each homework will be worth 10 points, and the homeworks all together will be worth 70% of the grade. The final comprehensive homework assignment will be worth 30% of the grade.

If you are taking the class for 4 credits, then there will also be a final project for the course. The final project must be turned in by the assigned final date before a grade for the class will be issued.

Homework

Homework 1 (due: Jan 22)

Homework 2 (due: Jan 29)

Homework 3 (due: Feb 05)

Homework 4 (due: Feb 12)

Homework 5 (due: Feb 19)

Homework 6 (due: Feb 26)

Homework 7 (due: Mar 05)

Homework 8 (due: Mar 12)

Homework 9 (due: Mar 26)

Homework 10 (due: Apr 02)

Homework 11 (due: Apr 09)

Homework 12 (due: Apr 16)

Homework 13 (due: Apr 23)

Homework 14 (due: Apr 30)

Comprehensive Homework (due: May 6)


Lectures

Lecture 01 - Jan 15, 2019

Lecture Slides

Lecture 02 - Jan 17, 2019

Lecture Slides

Lecture 03 - Jan 22, 2019

Lecture Slides

Lecture 04 - Jan 24, 2019

Lecture Slides

Lecture 05 - Jan 31, 2019

Lecture Slides

Lecture 06 - Feb 05, 2019

Lecture Slides

Lecture 07 - Feb 07, 2019

Lecture Slides

Lecture 08 - Feb 14, 2019

Lecture Slides

Lecture 09 - Feb 19, 2019

Lecture Slides

Lecture 10 - Feb 26, 2019

Lecture Slides

Lecture 11 - Feb 28, 2019

Lecture Slides

Lecture 12 - Mar 05, 2019

Lecture Slides

Lecture 13 - Mar 07, 2019

Lecture Slides

Lecture 14 - Mar 14, 2019

Lecture Slides

Lecture 15 - Mar 26, 2019

Lecture Slides

Lecture 16 - Mar 28, 2019

Lecture Slides

Lecture 17 - Apr 2, 2019

Lecture Slides

Lecture 18 - Apr 4, 2019

Lecture Slides

Lecture 19 - Apr 9, 2019

Lecture Slides

Lecture 20 - Apr 16, 2019

Lecture Slides

Lecture 21 - Apr 18, 2019

Lecture Slides

Lecture 22 - Apr 23, 2019

Lecture Slides

Lecture 23 - Apr 25, 2019

Lecture Slides IMP example from slides in updated rltool archive

Lecture 24 - Apr 30, 2019

Lecture Slides A

Lecture Slides B


Maude

Maude will be the primary tool used in this course, but several tools/libraries written in Maude will also be used. Some of these libraries require extra functionality to be added directly to Maude (at the C++ level). You can choose to build from the Maude sources or directly from binary releases of Maude 2.7.1.

# Download and unzip Maude 2.7.1 binary release for Linux
$ wget 'https://github.com/maude-team/maude/releases/download/v2.7.1-ext-hooks/maude-2.7.1-linux.tar.gz'
$ tar -xvf maude-2.7.1-linux.tar.gz
# Download Maude 2.7.1 binary release for MacOS
$ wget 'http://maude.cs.illinois.edu/w/images/2/25/Maude-2.7.1-osx.zip'
$ unzip Maude-2.7.1-osx.zip
# Run Maude
$ ./maude
\||||||||||||||||||/
--- Welcome to Maude ---
/||||||||||||||||||\
Maude 2.7.1 built: Aug 31 2016 18:22:38
Copyright 1997-2016 SRI International
Sun Oct 1 11:59:31 2017
Maude>

Maude Formal Environment (MFE)

The MFE packages together several tools which will be used in the course. It's recommended that you use the binary releases for anything needing the MFE. To get setup using MFE, you might do:

# Clone MFE
$ git clone 'https://github.com/maude-team/mfe'
# Launch Maude with MFE
$ ./maude mfe/src/mfe.maude
\||||||||||||||||||/
--- Welcome to Maude ---
/||||||||||||||||||\
Maude 2.7.1 built: Aug 31 2016 18:22:38
Copyright 1997-2016 SRI International
Sun Oct 1 11:51:55 2017
Full Maude 2.7e September 22th 2016
The Maude Formal Environment 1.0b
Inductive Theorem Prover - July 20th 2010
Sufficient Completeness Checker 2a - August 2010
Church-Rosser Checker 3p - August 30th 2016
Coherence Checker 3p - August 30th 2016
Maude Termination Tool 1.5j - August 11th 2014
Maude>

Note that many of the tools in the MFE cannot reason with built-in modules (many of the modules which come in prelude.maude). By default though, Maude includes the built-in module BOOL with any user-defined module. If you get the following error:

Error The use of built-ins is not supported by the checker.

be sure to disable including BOOL into your module by default:

set include BOOL off .

fmod MYMODULE is
    ...
endfm

If you are in loop mode (eg. if you have already loaded the MFE), then you must do this in parentheses:

(set include BOOL off .)

(fmod MYMODULE is
    ...
 endfm)

Sufficient Completeness Checker

The SCC tool works on an older version of Maude, and I only know of Linux binaries for it. Login to EWS or use a virtual machine if you are not on a Linux machine.

$ wget 'http://maude.cs.uiuc.edu/tools/scc/releases/Maude-ceta-2.3-linux.tgz'
$ tar -xvf Maude-ceta-2.3-linux.tgz
$ cd Maude-ceta-2.3-linux
$ ./maude-ceta
\||||||||||||||||||/
--- Welcome to Maude ---
/||||||||||||||||||\
Maude-ceta 2.3 built: Feb 18 2007 09:49:47
Copyright 1997-2007 SRI International
With CETA extensions Copyright 2006-2007
University of Illinois at Urbana-Champaign
Mon Oct 2 19:17:22 2017
# Load SCC
Maude> load scc.maude
# Start the SCC
Maude> loop init-cc .
Starting the Maude Sufficient and Canonical Completeness Checker.
# Load the file with module of interest (note that it should NOT be in parens)
Maude> load ../../../PATH/TO/FILE/WITH/MODULE/NOT/IN/PARENTHESES
# Select the CC-LOOP module.
Maude> select CC-LOOP .
# Check Sufficient Completeness (modulo other proof goals)
Maude> (scc MODULE-OF-INTEREST .)
Warning: no loop state.
Advisory: attempting to reinitialize loop.
Starting the Maude Sufficient and Canonical Completeness Checker.
Checking sufficient completeness of MODULE-OF-INTEREST ...
Success: MODULE-OF-INTEREST is sufficiently complete under the assumption that it is ground weakly-normalizing, confluent, and ground sort-decreasing.

Maude Inductive Theorem Prover

Go to the Maude ITP Webpage to download the sources for the Maude ITP. The Maude ITP runs on Maude 2.7.

Commands that you may find useful (see the tutorial on the Maude ITP website):

Using the example module from lecture 13 (say file nat-ord.maude):

fmod NATURAL-ORD is
  sort Natural .
  op 0 : -> Natural [ctor] .
  op s : Natural -> Natural [ctor] .
  op _<_ : Natural Natural -> Bool .
  op _=<_ : Natural Natural -> Bool .
  vars N M : Natural .
  eq N < 0 = false .
  eq 0 < s(N) = true .
  eq s(N) < s(M) = N < M .
  ceq N =< M = true if N < M .
  ceq N =< M = true if not(M < N) .
  ceq N =< M = false if M < N .
endfm

And an example interaction:

# Download and unpack the Maude itp
$ wget 'http://maude.cs.uiuc.edu/tools/itp/maude_itp.tar.gz'
$ tar -xvf maude_itp.tar.gz
\||||||||||||||||||/
--- Welcome to Maude ---
/||||||||||||||||||\
Maude 2.7 built: Oct 17 2017 22:51:54
Copyright 1997-2014 SRI International
Tue Oct 17 23:40:31 2017
Maude> load maude_itp/itp-tool.maude
Maude> load nat-ord.maude
Maude> select ITP-TOOL .
Maude> loop init-itp .
ITP tool (May 25th, 2006)
--- Introduce linearity goal
--- ------------------------
Maude> (goal linear : NATURAL-ORD |- A{N:Natural ; M:Natural} (((N =< M) or (M =< N)) = (true)) .)
rewrites: 1200 in 18ms cpu (18ms real) (66666 rewrites/second)
=================================
label-sel: linear@0
=================================
A{M:Natural ; N:Natural}
N:Natural =< M:Natural or M:Natural =< N:Natural = true
+++++++++++++++++++++++++++++++++
--- Use lemma of constants
--- ----------------------
Maude> (cns .)
rewrites: 223 in 3ms cpu (2ms real) (74333 rewrites/second)
New goals:
=================================
label-sel: linear@0
=================================
N*Natural =< M*Natural or M*Natural =< N*Natural = true
+++++++++++++++++++++++++++++++++
--- Split on N < M
--- --------------
Maude> (split on (N*Natural < M*Natural) .)
rewrites: 222 in 5ms cpu (5ms real) (44400 rewrites/second)
New goals:
=================================
label-sel: linear@1.0
=================================
N*Natural =< M*Natural or M*Natural =< N*Natural = true
=================================
label: linear@2.0
=================================
N*Natural =< M*Natural or M*Natural =< N*Natural = true
+++++++++++++++++++++++++++++++++
--- Discharge goal 1 with assumptions
--- ---------------------------------
Maude> (auto .)
rewrites: 112 in 0ms cpu (0ms real) (~ rewrites/second)
Eliminated current goal.
New current goal:
=================================
label-sel: linear@2.0
=================================
N*Natural =< M*Natural or M*Natural =< N*Natural = true
+++++++++++++++++++++++++++++++++
--- Discharge goal 2 with assumptions
--- ---------------------------------
Maude> (auto .)
rewrites: 54 in 0ms cpu (0ms real) (~ rewrites/second)
Eliminated current goal.
q.e.d
+++++++++++++++++++++++++++++++++