Ng Hiang Kwui黄炫圭


a.k.a. Xuangui HuangIn P.R. China we are forced to use names in Hanyu Pinyin, a romanization system for Mandarin Chinese, as our legal English names, regardless of the actual native languages we speak.

PhD Student
College of Computer and Information Science
Northeastern University

Office: 266 West Village HMailling address:
440 Huntington Ave.
202 West Village H
Boston, MA 02115
Emails: stslxg (at) /
Webs: My goodreads LinkedIn always spams my email. Boycott LinkedIn! The Nearly-dead Chinese facebook Chinese twitter

I have great enthusiasm for theoretical computer science, especially computational complexity. Currently I'm working on approximate degrees and data-structure lower bounds, advised by Prof. Emanuele Viola. I will visit the Simons Institute for the "Lower Bounds in Computational Complexity" program this fall.

Previously I earned my bachelor's and master's degrees from Shanghai Jiao Tong University, advised by Prof. Yijia Chen. During that period, I did research on parameterized complexity, circuit complexity, and descriptive complexity. I love to explore a wide range of research topicsI had done some research work on correlation decay, recursion theory, and equivalence checking. I also have some interest in principles of programming languages, especially type theory., to learn some latest big results/frameworks, and to attack challenging open problems.


  • Slicewise Definability in First-Order Logic with Bounded Quantifier Rank
    • with Yijia Chen and Joerg Flum, 26th EACSL Annual Conference on Computer Science Logic (CSL 2017)
    • manuscript, conference version
    • Using color-coding we demonstrate that some parameterized (hyper)graph problems can be slicewise-defined in $\mathrm{FO}_q$ where $q$ is independent of the parameter $k$, and prove the strictness of $\big(\mathrm{XFO}_{q} \big)_{q \in \mathbb{N}}$ by proving that $\mathrm{FO}_{q} \subsetneq \mathrm{FO}_{q+1}$ on arithmetical structures for every $q\in \mathbb{N}$
  • Algorithm for Relatively Small Planted Clique with Small Edge Probability
  • Ladner Theorem in Parameterized Complexity Theory
    • Undergraduate Thesis, supervised by Prof. Yijia Chen, 2014
    • We use finite injury priority method to prove that there are infinitely many $\mathrm{W[1]}$ problems that are neither $\mathrm{W[1]}$-Complete nor $\mathrm{FPT}$ if $\mathrm{FPT} \neq \mathrm{W[1]}$, presenting a "complete" proof which is more accessible to people not well-versed in recursion theory, compared with the original proof by Downey and Fellows

Academic Activities

Talks Given

2017 Autumn Special Topics in Complexity Theory
Foundations of Cryptography
Spring Master's Thesis Defense
2016 Spring Master's Thesis Openning Defense
2015 Autumn Holographic Algorithms and Counting Complexity
Spring Communication Complexity
2014 Autumn Advanced Topics on Computational Compleixty
Summer Finite Injury Method
Spring Kolmogorov Complexity

Summer Schools, Conferences, and Workshops Participated

2018 Feb. Workshop on Probabilistic and Extremal Combinatorics, Harvard
Jan. Innovations in Theoretical Computer Science, MIT
2017 Nov. Workshop on Algebraic Methods in Combinatorics, Harvard
Oct. Workshop on Additive Combinatorics, Harvard
July Swedish Summer School in Computer Science, KTH
2016 Aug. China Theory Week, CUHK
Summer School on Quantum Algorithms and Quantum Programming, GZU
July Coalgebraic Methods for Automata, ECNU
Highlights of Theoretical Computer Science, SHUFE
May Chinese Mathematical Logic Conference, Fudan
2015 Aug. China Theory Week, SJTU
July Logic Summer School in China, ZNU
2014 Aug. BASICS Summer School and Logic Summer School in China, SJTU
June IMS Graduate Summer School in Logic, NUS
May Annual Meeting of Asian Association for Algorithms and Computation, ZJU
2013 Sept. Asian Logic Conference, SYSU
Aug. Summer School on Verification on Infinite State Systems, SJTU
July Asian Initiative for Infinity (AII) Graduate Summer School, NUS

Teaching Assistantships

2016 Summer Theory of Computation, Fudan, for undergraduates
2015 Summer Advanced Algorithms, Fudan, for graduates
Spring Formal Semantics of Programming Languages, SJTU, for graduates
2014 Summer Advanced Algorithms, Fudan, for graduates
2013 Winter Algorithms, SJTU, for undergraduates

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