From abstract specs to practical protocols

In my previous post, I gave a brief visual interpretation to the latest paper by Vlad Zamfir, Nate Rush, Aditya Asgaonkar and Georgios Piliouras. We saw there that Casper CBC defines an abstract protocol specification, made up of validators sending messages to reach consensus. Once we prove some very nice properties on this general family of protocols, we can define a bit further some components of the mechanisms to obtain specific protocol instances. This is the magic of CBC: Do the hard work on the foundations and reap the profits downstream!

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CBC Casper can be refined to yield various specific consensus protocols, starting from its abstract specifications.

This article will build on the previous one, with…


With pictures!

A consensus protocol is a mechanism that provides guarantees for a set of communicating agents to agree on something. In the blockchain context, nodes that download new blocks want to make sure they agree on a set of transactions as canonical, a unique history of the system. With Proof of Work (PoW), as soon as a node solves the hashing puzzle with a set of transactions, it can publish this set with a proof of solution to its peers and hope to be included in the canonical chain.

The drawbacks of PoW have been widely covered: its extremely wasteful energy…


Taipei, in an effort to “green” the city after decades of industrialisation and develop alternative modes of transportation, has steadily built a large network of bicycle lanes. The more awkward ones run on parts of sidewalk with two simple parallel lines delineating the space, but the more scenic paths are to be found along its rivers. Though flanked on every side by turbulent expressways and large interchanges feeding into long bridges, once an opening below the motorised hell is passed, you finally access the riverbeds. …


Cities may come in all sizes and shapes, cultures and habits, histories and topologies but still remains one seemingly common denominator across all: the pedestrian. Yes, people in New York walk faster (but slower than Singapore, apparently, though the study discounts pedestrians using their phone while walking, which accounts for 90% (data mine, totally objective) of everyone), people in Bangalore seamlessly move from sidewalk to the road, people in Hong Kong know to arrange themselves in queues in congested areas, but even these specificities can be explained away by the particular conditions in which they happen.

One constant aspect of…


I have skipped a week in my year of writing but will make it up now with some stray thoughts.

I went to Taiwan in 2015 and really enjoyed my time there. I could tell you about the countless amazing things I have seen and done, my aborted 3-day bicycle trip in pouring rain, the great food and people, but that would take a lot more time! I will focus on a teeny tiny detail that caught my attention and that links especially well to some of my previous articles.

Social norms and values are always a tough subject. Economists…


My first musical memory is playing the first song off of The Verve’s Urban Hymns album, the super famous “Bitter Sweet Symphony”, on repeat, when I was five years old. The CD my parents bought had somehow found its way to the oversized boombox I was keeping in my room from time to time. To this day, I have no idea what the rest of the album sounds like, even when it has haunted my iTunes Library since 2009, when I started ripping our CD collection.

Being born in the early nineties, I somehow met and used a large number…


For a long time, it felt difficult to properly pin down what exactly I was doing in my PhD. It was too far from the maths I studied, and it was neither computer science nor economics, but had elements of both. The answer might have been hiding in plain sight. My department’s name, Engineering Systems & Design, is really the most apt description.

What does that look like? In a previous post, I argued that Design should be understood in the sense of Economics, implying that our department is a hybrid of Engineering and Economics: engineering as the optimising machine…


I have now spent three and a half years in the Singapore University of Technology and Design. It is pretty clear what the first qualifier, Technology, is, but the second, Design, is thrown around a lot to finally encompass many different things. This article argues that design is approximately a fancy term for economics. Later on, I ramble on about design and emotional connection with the things around us.

Design is functional, technology is functionless

When I was 13, in the last year of middle school, my mother, a fan of Philippe Starck, enrolled me in a weekly class of “Design”. Unsure of what to expect…


Behind the oversized backpack a little man is running around between the tables and stalls of the food court. He stops and turns whimsically, sometimes pausing in front of a steaming glass panel, tiptoeing to see what is cooking, both hands applied on the warm and sweaty separation. The noodles jump in the wok while the morning-prepared shrimps wait for their turn, long flames form under the concave steel.

His sister pulls the back handle of his bag, he shrieks but eventually retraces her bouncing steps around the hall to check out another stall. The cook there tied a red…


(Some spoilers… but you have seen the movie, right?)

One recent discussion with one of my advisors brought up the subject of game theory crossing over to movies. It prompted me to think about which movies featured a typical game-theoretic situation, where players act competitively (or cooperatively) and receive a payoff from their actions. If this sounds abstract, let me introduce the idea with a game theory flavoured reading of The Dark Knight.

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Knowing the other

Before we start, let’s set up the stage for the coming discussion. A situation can be written in terms of game theory if two (or more) players…

Barnabé Monnot

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