Jason Hu

a.k.a. Zhong Sheng Hu

I am currently a PhD student at McGill University, under the supervision of Professor Brigitte Pientka. I did my Master of Mathematics at the University of Waterloo, supervised by Professor Ondřej Lhoták. Before that, I worked in the industry since 2014. My undergrad was at Fudan University.
These days, I am mainly working on programming languages and formal proofs using proof assistants based on Martin-Löf type theory, e.g. Coq and Agda. I am particularly interested in various type theories and the mathematics behind them. As a purist, I insist that if a proof can be done constructively, then it needs to be; if a mechanized proof can be established, there is no reason not to.
Before heading back to school, I worked as an engineer on a number of projects involving performance engineering, configurations, and others that you might expect to see in the industry. Back in my old days at Fudan University, I was more of a robotic guy.
I am in support of 996.icu activity 996.icu.


Education

McGill University

Montreal, QC

Doctor of Philosophy
Computer Science

Grade: NA

Courses:
  • COMP 550 Natural Language Processing
09 / 2019 - present

University of Waterloo

Waterloo, ON

Master of Mathematics
Computer Science

Grade: 94.4/100

Thesis: Decidability and Algorithmic Analysis of Dependent Object Types (DOT) (code) (slides)

Investigation on (un)decidability and algorithmic properties of the family of DOT calculi

Abstract

Dependent Object Types, or DOT, is a family of calculi developed to study the Scala programming language. These calculi have path dependent types as a feature, and potentially intersection types, union types and recursive types. So far, the study of DOT calculi mostly focuses on the soundness proof, which does not directly contribute to development of compilers. This thesis presents a detailed investigation of decidability and algorithmic properties of the family of DOT calculi.
In decidability analysis, the undecidability of subtyping of several calculi is formally established, including the D<: and D∧ calculi. Prior to this investigation, the undecidability of subtyping of all DOT calculi including D<: was open. Decidability analysis puts emphasis on a particular form of subtyping rules, called normal form. It turns out that a normal form definition is not only as expressive, but also more suggestive than the original definition. A conceptual device, called small-step analysis, is introduced to assist converting a usual definition of subtyping to its normal form definition. Moreover, decidability analysis gives direct contributions to the algorithmic analysis, by revealing two decidable fragments of D<: in declarative form, called the kernels. Decidability analysis also suggests a novel subtyping algorithm framework, stare-at subtyping. Stare-at subtyping and an existing algorithm are shown to be sound and complete w.r.t. their corresponding kernels.
In algorithmic analysis, stare-at subtyping is extended to other calculi, with more features than D<:, including D∧, μDART and jDOT. In μDART and jDOT, bi-directional type assignment algorithms are developed. The algorithms developed in this thesis are all shown to be sound with respect to their target calculi and terminating.
During the development of the algorithms, analysis shows a number of ways in which the Wadlerfest DOT calculus does not directly correspond to the Scala language, while substantially increases the difficulties of algorithmic design. jDOT, therefore, is developed as an alternative formalization of Scala.

Courses:
  • CS 341 Algorithms
  • CS 745 Computer-Aided Verification
  • CS 766 Theory of Quantum Information (report)
  • ECE 653 Software Testing, Quality Assurance and Maintenance
  • CS 860 Advanced Topics in Algorithms and Complexity (report)
09 / 2017 - 08 / 2019

Fudan University

Shanghai, China

Bachelor of Science
Electronic Engineering

Grade: 3.35/4.0

09 / 2010 - 07 / 2014

publications

Undecidability of D<: and Its Decidable Fragments (To Appear)

POPL'20

Jason Hu and Ondřej Lhoták
2020

Teaching

McGill University

Montreal, QC

Teaching Assistant

COMP 360, Algorithm Design

09 / 2019 - present

University of Waterloo

Waterloo, ON

Teaching Assistant / Instructional Apprendice

CS 241, Foundation of Sequentual Programs
CS 343, Concurrent and Parallel Programming

09 / 2017 - 08 / 2019

Activities

Oregon Programming Languages Summer School

student

with fellowship

2019

American Mathematical Society

student member

2018

DeepSpec Summer School

student

2018

Industry

Morgan Stanley Services Canada Corp.

Montreal, QC

Summer Analyst Intern
05 / 2018 - 08 / 2018

Morgan Stanley Services Canada Corp.

Montreal, QC

Java / Scala Developer
10 / 2015 - 07 / 2017

Nexsan Technologies

Dorval, QC

Software Developer
08 / 2014 - 10 / 2015

Gridsum Technologies

Shanghai, China

.Net Engineer Intern
05 / 2014 - 06 / 2014

Virtuos

Shanghai, China

QA Intern
07 / 2013 - 08 / 2013

Other Info

I speak four languages: English, Mandarin, Cantonese and Japanese.
I had 6 years of math, 2 years of physics and 1 year of chemistry olympiads experience.
I am a Cantonese. My town is Foshan. Warning: I've got no idea how to perform Wing Chun.


Interests

I like superheroes, Marvel, DC and whatever you can name.
I used to play badminton during undergrad at Fudan with friends, but it turns out that it's hard to even find a reasonable court and shop for maintenance in Canada!
I have lots of video games in my Steam library, and I dream to have time to play!