Verified Systems Engineering @ NUS
Building trustworthy safety-critical systems and advancing the state of the art in formal verification

About Us

Group photo

We do research in the design and implementation of programming languages (PL), mathematical models of computation, and computer-assisted formal reasoning, at School of Computing at National University of Singapore.

Our results address software reliability issues that arise in everyday job of software developers. we do so by investigating theoretical foundations and building tools for ensuring that certain kinds of costly software errors and vulnerabilities never occur in the real-world code, which many people rely upon in their everyday lives.

Our current investigations follow the themes outlined below.

For more details on our research, check out our blog posts, projects, and recent papers.

Theme 1: Trustworthy Distributed Systems

It is hard to overstate the significance and ubiquity of distributed services in many aspects of modern life, such as health care, online commerce, transportation, entertainment and cloud-based applications. Given the importance of distributed software and its complexity, it is vital in industry to have a rigorous verification methodology for establishing its correctness properties, ensuring that, once a distributed system is up and running, it will never go wrong and will eventually complete its goals.

Our recent work has established logical foundations for compositional verification of complex distributed protocols using a proof assistant. We have also produced the first mechanically verified proof of safety of Nakamoto consensus. Our ongoing work builds libraries and techniques for mechanised reasoning about probabilistic properties of distributed protocols and data structures employed by them. In particular, we have produced the first mechanised proof of the false-positive ratio for Bloom filters (see this blog post for more details).

Theme 2: PL Design for Distributed Programming

In this line of research we apply core PL techniques, such as semantics, type systems, and abstract interpretation, for building safe and secure decentralised applications.

For instance, in our recent work, inspired by the verification ideas from Theme 1, we have developed a library for compositional construction of distributed protocols, allowing their modular testing and model-checking. By reflecting on the analogy between design principles of secure smart contracts (a particularly prominent class of decentralised applications) and concurrent software (also see the related ACSAC'18 and ISSTA'19 papers), in collaboration with industry partners we have developed Scilla, a functional smart contract language with strong safety guarantees. We have also developed a set of efficient compilation techniques for Scilla as well as a Coq-powered verification methodology for it.

Our ongoing research explores opportunities for (a) developing low-overhead abstractions for automated reasoning about distributed applications and (b) enhancing parallelism offered by modern distributed protocols via programming language techniques.

Theme 3: Program Synthesis and Repair

Program synthesis is an emerging research and technology paradigm for automatically deriving programs from user-provided declarative specifications, thereby significantly reducing the implementation effort required for producing correct-by-construction and efficient code.

Our recent work explored applications of state-of-the-art techniques for analysis, verification, and deductive proofs for fast and expressive program synthesis (check out the papers on SuSLik, ROBoSuSLik, and SuSLik 2.0: Cypress) and for program repair. Our long-term agenda involves synthesis of correct concurrent and distributed programs by adopting our work on static analysis and logical foundations for reasoning about concurrent and distributed systems.



Ilya Sergey
Ilya Sergey


Andreea Costea
Andreea Costea
Yutaka Nagashima
Yutaka Nagashima

Graduate Students

Kiran Gopinathan
Kiran Gopinathan
Yunjeong Lee
Yunjeong Lee
George Pîrlea
George Pîrlea
Yasunari Watanabe
Yasunari Watanabe



May 25

The paper on Cyclic Program Synthesis has been named a recipient of PLDI 2021 Distinguished Paper Award.

May 04

Two papers, on smart contract sharding and on cyclic program synthesis, will appear at PLDI'21.

Apr 15

Yasunari Watanabe has defended his MComp thesis on Certified Program Synthesis. Congratulations, Yasu!

Dec 01

Yutaka Nagashima joins the team as a postdoc. Welcome, Yutaka!

Nov 30

Our paper on Automated Repair of Heap-Manipulating Programs via SuSLik-style Synthesis will appear at VMCAI 2021.


Synthesis of Heap-Manipulating Programs from Separation Logic specifications.
A functional language for safe smart contracts.
Static automated concurrency repair at scale.
Verified hash-based approximate membership structures.
A Coq implementation of a minimalistic blockchain-based consensus protocol.
Mechanised Separation Logic for Compositional Verification of Distributed Protocols.



Practical Smart Contract Sharding with Ownership and Commutativity Analysis
George Pîrlea, Amrit Kumar and Ilya Sergey

2021 ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI 2021). Taking place virtually, June 2021.

Cyclic Program Synthesis
Shachar Itzhaky, Hila Peleg, Nadia Polikarpova, Reuben Rowe and Ilya Sergey

2021 ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI 2021). Taking place virtually, June 2021. PLDI 2021 Distinguished Paper Award.

A Framework for Certified Program Synthesis
Yasunari Watanabe

MComp Thesis. NUS School of Computing, 2021.

Testing Static Code Analyses with Monadic Definitional Interpreters
Tram Hoang

Capstone Thesis. Yale-NUS College, 2021.

Towards Enhancing Deductive Synthesis of Heap-Manipulating Programs with Examples
Bryan Tan Yao Hong

Capstone Thesis. Yale-NUS College, 2021.

Towards User-Friendly Linearizability Checking
Alaukik Nath Pant

Capstone Thesis. Yale-NUS College, 2021.

A Study of Control and Type-Flow Analyses for Higher-Order Programming Languages
Gabriel Petrov

Capstone Thesis. Yale-NUS College, 2021.

Towards Locally-Parallel Processing of Smart Contract Transactions
Nicholas Chin Jian Wei

Capstone Thesis. Yale-NUS College, 2021.

Automated Repair of Heap-Manipulating Programs using Deductive Synthesis
Thanh-Toan Nguyen, Quang-Trung Ta, Ilya Sergey and Wei-Ngan Chin

22nd International Conference on Verification, Model Checking, and Abstract Interpretation (VMCAI 2021). Copenhagen, Denmark, January 2021.

Protocol Combinators for Modeling, Testing, and Execution of Distributed Systems
Kristoffer Just Arndal Andersen and Ilya Sergey

Accepted for publication in Journal of Functional Programming in 2021. Cambridge University Press.

Verified Systems Engineering
Yale-NUS College
NUS School of Computing