CUT TO:
INT. PROJECT ARCHIVE — STORYBOARD ROOM
The USER opens Program Specification & Verification with Dafny.
DIVAKAR DESSAI
Let's run through the shots.
CASE FILE / SENG2011 / Formal Methods
Program Specification & Verification with DafnyProving Behaviour Instead of Testing Examples
Used Dafny predicates, contracts and quantifiers to formally specify and verify program properties across all valid inputs.
01–02 / OPENING SEQUENCE
Establishing the world
01 / Establishing Shot
The Problem
Traditional tests demonstrate behaviour for selected inputs, while the assignment required expressing properties strongly enough for a verifier to prove them for every permitted input.
02 / Wide Shot
The Context
The project introduced formal specification and verification using Dafny.
03 / CHARACTER NOTE
DIVAKAR'S ROLE
Subject
Divakar Dessai
Production
Program Specification & Verification with Dafny
Take
03 / Role
Role notes
DIVAKAR DESSAI
I wrote predicates, contracts and validation cases and used Dafny to prove whether implementations satisfied those specifications.
04 / CLOSE-UP
THE ENGINEERING CHALLENGE
Requirements expressed informally in English had to be translated into precise mathematical statements without accidentally weakening or over-constraining them.
05 / TRACKING SHOT
THE APPROACH
A plan emerges.
I represented requirements using predicates, quantifiers, preconditions and postconditions and iteratively refined them until Dafny could establish the required proofs.
06 / INSERT SHOTS
KEY FEATURES
The system takes shape.
07 / DIRECTOR'S NOTES
DESIGN DECISIONS
Things we decided along the way
01
Specified desired behaviour independently from implementation details.
02
Used quantified expressions to describe whole-array properties.
03
Included circular boundary relationships explicitly in specifications.
design decisions
somewhere mid-build
08 / RETAKES
WHAT WENT WRONG
Naturally, not everything cooperates.
09 / FINAL SHOT
THE OUTCOME
ProblemBuildOutcome
01
Developed practical experience with formal verification.
02
Learned to distinguish tests from mathematical correctness arguments.
03
Improved precision when specifying software behaviour.
10 / PRODUCTION NOTES
TECH STACK
The tools behind the scenes.
DafnyFormal VerificationPredicatesQuantifiers
11 / BEHIND THE SCENES
LINKS
FADE OUT.
USER closes the file.
One project down. A few more stories left.
DIVAKAR DESSAI
Pick another?