Research Interests
Software verification; Security; Program Synthesis and Machine Learning; Logic and automata theory;
Outreach Interests
ConTraIL project: Privacy-preserving contact tracing project.
See
Whitepaper.
Current research projects and philosophy
My general research philosophy is to turn the theory lens (mainly logic
and algorithms) towards practical computing domains.
I shy away, for the most part, from working on problems
purely motivated by theoretical concerns as well as those entirely
based on heuristics to solve practical problems.
My current research interests are primarily in automating software
verification, building correct-by-design secure distributed systems,
and exploring synergies between machine learning
and program synthesis for building intelligent systems.
Automating software verification:
Proving a program safe using logical techniques is composed
of two phases: finding possible inductive invariants and formally
establishing that they are inductive invariants that prove safety.
For the latter problem, the main approach that I currently believe in
for automation is the framework of
natural proofs that we have been working on for the last
10 years.
In particular, though I believe decidable
logics are useful for this problem, I do not
believe they will solely be powerful enough for addressing the needs
of program verification, due to their inherent inexpressivity.
Natural proofs aim for sound and oftentimes complete (though not decidable)
approaches for this problem.
As for the former problem for finding invariants, I believe that a
combination of several techniques that are proposed in recent literature
(including interpolation and IC3) are called for. The primary techniques
techniques I work on have been those based on learning and (more recently)
finding
uninterpreted invariants.
Building verified systems:
My view on building verified systems is that they should be
built correct by construction (as opposed to verifying existing systems),
by proving more abstract systems correct and then refining them
to concrete performant code. The proofs of abstract systems
against complex specifications would invariably require considerable
human input and intuition, while automation can help in refining
abstract systems to performant code.
Machine Learning and Program Synthesis:
One of my latest interests is in building synergies of
program synthesis and
machine learning--- I believe practical pattern-matching inductive
techniques (like neural nets) can be combined with symbolic search
(like synthesizing logical formulas and programs) to build more
intelligent systems.
Note to prospective students
I am actively looking for Ph.D. students in the following areas. If
you are interested, please apply for the Ph.D. program and write to me
personally.
Machine learning and program synthesis; learning logics.
Exploring new techniques that go beyond neural nets by
using symbolic search, abstraction, and reasoning.
Building verified software using almost-automated verification,
especially distributed systems that involve crptography,
like blockchains, bitcoin, and smart contracts.
Logics and reasoning for program verification: especially logics
involving expressive specifications for programs manipulating
quantified specifications and datastructures. See papers on
natural proofs in POPL 2012, PLDI 2013, PLDI 2014, and POPL 2018,
and the Dryad and VCDryad) pages.
Invariant synthesis and mining specifications from code
using machine learning, online learning,
and learning logical formulas. See papers in CAV14, POPL16, TACAS16, TOCL18, TACAS18, OOPSLA18.
Exploring the world of uninterpreted programs--- we have discovered
a new technique for verifying uninterpreted programs using
complete/decidable techniques for generating inductive invariants.
This opens up a wide avenue for future work--- tracttable
verification, invariant synthesis, synergy with natural proofs, and
program synthesis.
Earlier research Projects
Decidable logics for reasoning with heaps/dynamic data structures (Strand)
Security of web browser extensions (VEX)
Testing concurrent programs (Penelope)
Security of access control (VAC)
Annotation and proof mechanisms for safe concurrency (Accord)
Model-checking abstractions of programs (Getafix)
Decidable automata models (See page on visibly pushdown automata)
Software/tools:
VCDryad - An extension of VCC that provides sound but incomplete automatic
mechanisms against Dryad specifications, a dialect of separation logic.
Dryad - Sound but incomplete mechanism for proving heap-based programs correct
CAV 2013 tool - for learning universally quantified invariants on linear data-structures using quantified data automata
Strand - Decidable logics/SMT solver for reasoning with heaps
Getafix - A boolean model-checker for concurrent and recursive programs
VEX - Static analysis of web-browser extensions for security vulnerabilities
Penelope - A testing tool for concurrent programs
VAC - Verifier of Access Control
JIST - Java Interface Synthesis Tool
Students and Post-doctoral researchers:
Students currently advised:
Angello Astorga (mining program specifications), jointly advised with Tao Xie
Adithya Murali (combining machine learning and program synthesis; learnin logics)
Shambwaditya Saha (synthesis, learning, mining specifications)
Formerly advised:
Students:
Pranav Garg (deductive verification; compositional verification)
Edgar Pek (static analysis; points-to analysis)
Francesco Sorrentino (testing concurrent programs)
Xiaokang Qiu
Thesis: Automatic Techniques for Proving Correctness of Heap-Manipulating Programs
Now postdoc at MIT/UMD.
Sruthi Bandhakavi; security of web extensions -- now at Google
Postdocs:
Gennaro Parlato -- now faculty at University of Southampton
Karl Palmskog-- now a postdoc at UT Austin.
Daniel Neider (automated deductiver verification, synthesis, learning, invariant synthesis)
Post-doctoral researcher in the ExCAPE project, jointly at Illinois and UCLA.
-- now at Max Planck Institute
Courses:
Note to graduate students: If you are interested in mainstream software verification, I suggest that you take the course CS477 (Formal Methods in Software Development) followed by my course CS598MP (offered only once in a while) on Software Verification.
The CS598MP course is more advanced, and CS477 will be a pre-requisite for it in the future.
I also strongly encourage you to take the CS498 course on "Logic in Computer Science" (aka Logical Systems) offered by me or Prof. Viswanathan before you take CS58MP:Software Verification.
Spring '14:
CS498: Logic in Computer Science
Fall '13:
CS173: Discrete Structures
Fall '11:
CS373: Intro to Theory of Computation
Spring '11:
CS477: Formal Methods in Software Development
Earlier courses
Also check out the following:
Formal Methods Seminar at Illinois
The new Formal Methods Reading List
Service
PC Member: POPL 2019
PC Member: CONCUR 2018
PC Member: Workshop on Automated Deduction for Separation Logics (ADSL), affiliated with LICS and FLOC, 2018.
PC Member: TACAS 2017
PC Member: Highlights of Logic, Automata, and Games, 2017.
PC Member: International Conference on Runtime Verification (RV 2017).
Tutorial on Machine-learning based methods for synthesizing invariants.
, at Computer Aided Verification (CAV), San Fransisco, USA, 2015.
PC Member: ICALP 2016: Int'l Colloq. on Automata Languages and Programming, Rome, Italy.
External Review Committee: CAV 2016: Computer Aided Verification, Toronto, Canada.
Co-chair/Organizer: SYNT 2015: 4th Workshop on Synthesis (associated CAV), San Francisco, USA.
PC Member: Trustworthy Global Computing (TGC), 2015, Madrid, Spain.
ERC Member: PLDI 2015, Portland, Oregon, USA.
PC Member: ACM/IEEE International Conference on
Model Driven Engineering Languages and Systems, 2014, Madrid, Spain.
PC Member: POPL 2015, Mumbai, India.
PC Member: PLDI 2014, Edinburgh, Scotland.
PC Member: CONCUR 2014, Rome, Italy
PC Member: SAS 2014, Munich, Germany
Earlier
2013: PC Member: MFCS, 2013, CAV 2013, Highlights of Logic, Automata, Games
2012: PC Chair: CAV 2012; PC Member: LPAR-18, POPL 2012.
2011: PC Member: CAV 2011, ATVA 2011, FSTTCS 2011.
2010: PC Member: FSTTCS 2010, ATVA 2010,
STACS 2010,
2009: PC member: CAV 2009,
LICS 2009, TIME 2009; Ext Rev Committee: PLDI 2009
2008: PC Member: APLAS 2008, CONCUR 2008.
2007 PC Chair: INFINITY 2007 (with CONCUR); PC Member: ICALP 2007
2006 PC member: ACM SAC.
2005 PC member: FSTTCS 2005, CAV 2005.
GDV 2005 (with CAV'05).
2004 PC member: FORMATS and FTRTFT, 2004
Other Activities: Organized events, invited talks, etc.