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Quan Hoang Nguyen

Quan Hoang Nguyen
Fantom Foundation

Doctor of Philosophy

About

47
Publications
58,534
Reads
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256
Citations
Citations since 2016
26 Research Items
171 Citations
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Introduction
Quan Nguyen is doing R&D on Blockchains and Distributed Ledger at Fantom Foundation. His interests include Distributed & Cloud, Web Apps, InfoVis, Programing Languages, Semantics and Code Optimization. His homepage is at: https://quannguyenh.github.io. Note: I no longer work at InfoVis, Sydney University since June 2018.
Additional affiliations
February 2020 - March 2020
Fantom Foundation
Position
  • Researcher
Description
  • Head Researcher and Developer. Interested in DLT, Smart contracts. Advisors: Andre Cronje
November 2019 - present
Fantom Foundation
Position
  • Lead Architect
Description
  • Software Architect and Chief Scientist. Interested in DLT. Advisor: Andre Cronje
October 2018 - present
Fantom Foundation
Position
  • Research Lead (Consensus)
Description
  • Interested in DLT. Advisor: Andre Cronje
Education
February 2010 - January 2013
The University of Sydney
Field of study
  • Visualization of Big Graphs
September 2006 - July 2009
UNSW Sydney
Field of study
  • Validity contracts for software transactions

Publications

Publications (47)
Preprint
Full-text available
This paper consolidates the core technologies and key concepts of our novel Lachesis consensus protocol and Fantom Opera platform, which is permissionless, leaderless and EVM compatible. We introduce our new protocol, so-called Lachesis, for distributed networks achieving Byzantine fault tolerance (BFT)~\cite{lachesis01}. Each node in Lachesis prot...
Experiment Findings
Simple questions were sent to the people who were supposed to know the meaning of integrity. No answer. The questions were very simple and many people around the world can answer very quickly.
Preprint
Full-text available
Smart contract (SC) platforms form blocks of transactions into a chain and execute them via user-defined smart contracts. In conventional platforms like Bitcoin and Ethereum, the transactions within a block are executed \emph{sequentially} by the miner and are then validated \emph{sequentially} by the validators to reach consensus about the final s...
Preprint
Full-text available
Byzantine fault tolerance (BFT) has been extensively studied in distributed trustless systems to guarantee system's functioning when up to 1/3 Byzantine processes exist. Despite a plethora of previous work in BFT systems, they are mainly concerned about common knowledge deducible from the states of all participant processes. In BFT systems, it is c...
Experiment Findings
- Open questions and discussions with world-wide scholars. - Provide the context with description and related links for the participants to read and add discussions. - Direct the participants to answer the questions, if possible.
Preprint
The problem of peer selection, which randomly selects a peer from a set, is commonplace in Proof-of-Stake (PoS) protocols. In PoS, peers are chosen randomly with probability proportional to the amount of stake that they possess. This paper presents an approach that relates PoS peer selection to Roulette-wheel selection, which is frequently used in...
Experiment Findings
Open questions were raised and open discussions are encouraged from world-wide researchers and readers who are interested in the questions.
Preprint
Full-text available
This paper introduces a new consensus protocol, so-called \emph{\stair}, for fast consensus in DAG-based trustless system. In \stair, we propose a new approach to creating local block DAG, namely \emph{x-DAG} (cross-DAG), on each node. \emph{\stair} protocol is based on our Proof-of-Stake StakeDag framework \cite{stakedag} that distinguishes partic...
Preprint
Full-text available
Trustless systems, such as those blockchain enpowered, provide trust in the system regardless of the trust of its participants, who may be honest or malicious. Proof-of-stake (PoS) protocols and DAG-based approaches have emerged as a better alternative than the proof of work (PoW) for consensus. This paper introduces a new model, so-called \emph{\s...
Preprint
Full-text available
This paper presents a new framework, namely \emph{\onlay}, for scalable asynchronous distributed systems. In this framework, we propose a consensus protocol $L_{\phi}$, which is based on the Lachesis protocol~\cite{lachesis01}. At the core of $L_{\phi}$ protocol, it introduces to use layering algorithm to achieve practical Byzantine fault tolerance...
Preprint
Full-text available
We describe \emph{Fantom}, a framework for asynchronous distributed systems. \emph{Fantom} is based on the Lachesis Protocol~\cite{lachesis01}, which uses asynchronous event transmission for practical Byzantine fault tolerance (pBFT) to create a leaderless, scalable, asynchronous Directed Acyclic Graph (DAG). We further optimize the \emph{Lachesis...
Preprint
Full-text available
This paper introduces a new family of consensus protocols, namely \emph{Lachesis-class} denoted by $\mathcal{L}$, for distributed networks with guaranteed Byzantine fault tolerance. Each Lachesis protocol $L$ in $\mathcal{L}$ has complete asynchrony, is leaderless, has no round robin, no proof-of-work, and has eventual consensus. The core concept o...
Poster
This poster introduces a SPQR-based proxy approach for large graph visualization
Article
Full-text available
Common quality metrics of graph drawing have been about the readability criteria, such as small number of edge crossings, small drawing area and small total edge length. Bold graph drawing considers more realistic drawings consisting of vertices as disks of some radius and edges as rectangles of some width. However, the relationship that links thes...
Article
Full-text available
Spectral sparsification is a general technique developed by Spielman et al. to reduce the number of edges in a graph while retaining its structural properties. We investigate the use of spectral sparsification to produce good visual representations of big graphs. We evaluate spectral sparsification approaches on real-world and synthetic graphs. We...
Article
Full-text available
Data sampling has been extensively studied for large scale graph mining. Many analyses and tasks become more efficient when performed on graph samples of much smaller size. The use of proxy objects is common in software engineering for analysis and interaction with heavy objects or systems. In this paper, we coin the term ’proxy graph’ and empirica...
Article
Full-text available
Readability criteria have been addressed as a measurement of the quality of graph visualizations. In this paper, we argue that readability criteria are necessary but not sufficient. We propose a new kind of criteria, namely faithfulness, to evaluate the quality of graph layouts. We introduce a general model for quantify faithfulness, and contrast i...
Article
A common representational style for drawing graphs is the so-called circular drawings, where vertices are represented as points on a circle, and edges are represented as straight line segments. In such drawings, edges may cross; these edge crossings have a negative effect on human readability. Recent empirical research shows that increasing the ang...
Thesis
Full-text available
Graph visualizations create pictures to ease the understanding of network-structured data, especially in today’s big data era. Graphs become larger and more complex (e.g., multiple attributes and high connectivity) and are dynamically generated from modern applications ranging from social networks, financial industry to biology. Visualization metho...
Conference Paper
This paper is motivated by empirical research that has shown that increasing the angle of edge crossings reduces the negative effect of crossings on human readability. We investigate circular graph drawings (where each vertex lies on a circle) with large crossing angles. In particular, we consider the case of right angle crossing (RAC) drawings, wh...
Conference Paper
Full-text available
Graph drawing algorithms developed over the past 30 years aim to produce “readable” pictures of graphs. Here “readability” is measured by aesthetic criteria, such as few crossings or few edge bends or small grid drawing area. However, the readability criteria for visualizing graphs, though necessary, are not sufficient for effective graph visualiza...
Conference Paper
Graph streams have been studied extensively, such as for data mining, while fairly limitedly for visualizations. Recently, edge bundling promises to reduce visual clutter in large graph visualizations, though mainly focusing on static graphs. This paper presents a new framework, namely StreamEB, for edge bundling of graph streams, which integrates...
Conference Paper
Full-text available
Edge bundling methods became popular for visualising large dense networks; however, most of previous work mainly relies on geometry to define compatibility between the edges. In this paper, we present a new framework for edge bundling, which tightly integrates topology, geometry and importance. In particular, we introduce new edge compatibility mea...
Conference Paper
Recent empirical research has shown that increasing the angle of crossings reduces the effect of crossings and improves human readability [5]. In this paper, we introduce a post-processing algorithm, namely MAXCIR, that aims to increase crossing angles of circular layouts by using Quadratic Programming. Experimental results indicate that our method...
Chapter
Full-text available
In this paper, we present new visual analysis methods for history of the FIFA World Cup competition data, a social network from Graph Drawing 2006 Competition. Our methods are based on the use of network analysis method, and new visualization methods for dynamic graphs with dynamic hierarchy and geographic clustering. More specifically, we derive a...
Thesis
Full-text available
Software Transactional Memory is a promising approach to concurrent programming, freeing programmers from error-prone concurrency control decisions. But few such systems address consistencies of transactional objects. In this thesis, I propose a contract-based transactional programming model toward more secure transactional softwares. In this mode...
Conference Paper
Full-text available
This paper describes a generalisation of modulo scheduling to parallelize loops for SpMT processors that exploits simultaneously both instruction-level parallelism and thread-level parallelism while preserving the simplicity and effectiveness of modulo scheduling. Our generalisation is simple, drops easily into traditional modulo scheduling algorit...
Conference Paper
This paper describes a graph coloring compiler framework to allocate on-chip SRF(Stream Register File) storage for optimizing scientific applications on stream processors. Our framework consists of first applying enabling optimizations such as loop unrolling to expose stream reuse and opportunities for maximizing parallelism, i.e., overlapping kern...
Conference Paper
Full-text available
Many dynamic networks have associated geological information. Here we present two complementing visual analysis methods for such networks. The first one provides an overview with summerized information while the second one presents a more detailed view. The geological information is encoded in the network layout, which is designed to help maintain...
Conference Paper
Full-text available
Existing methods place data or code in scratchpad memory, i.e., SPM by either relying on heuristics or resorting to integer programming or mapping it to a graph coloring problem. In this work, the SPM allocation problem is formulated as an interval coloring problem. The key observation is that in many embedded applications, arrays (including struct...
Article
Full-text available
Static Single-Assignment (SSA) form is an efficient intermediate representation used in virtual machines and modern compilers. It provides data flow information that simplifies the implementation of standard program optimisations such as constant propagation, dead code elimination, and partial redundancy elimination. Constructing SSA form involves...
Article
Full-text available
Planarisation of graphs is a well studied research problem in Graph Theory and has important applications in Graph Drawing to draw non-planar graphs with as few crossings as possible. However, the problem of flnding the maximum vertex (or edge) induced planar subgraph NP-hard. Centrality index is one of the important concepts in Network Analysis fo...

Questions

Questions (25)

Network

Cited By

Projects

Projects (8)
Project
Applications of blockchains
Project
Working on novel approaches to addressing security and scalability of smart contracts.
Project
DLT, Blockchains, Decentralization