As is well-known by now, the universal AI agent AIXI is made up of two key components: Solomonoff Induction for universal sequential prediction, and expectimax search for planning. There are several proposed and reasonably effective approximations of the Solomonoff Induction component using the factored, binarised Context Tree Weighting algorithm [WST95, VNHUS09] and its generalisation to … More Approximating Solomonoff Induction
Have you ever wondered why the natural exponential function shows up so frequently in mathematical inequalities? Here’s a graph of the natural exponential function. The constant e has a special place in mathematics, which is beautifully chronicled in Eli Maor’s book [M94]. The definition of e that is most useful and intuitive for our purpose … More Natural Exponential Functions in Inequalities
A key claim of differential privacy in [DR14] is that it provides “automatic neutralization of linkage attacks, including all those attempted with all past, present, and future datasets and other forms and sources of auxiliary information”. This is an important and often repeated claim — see e.g. [N17, Section E] and [PR23] — but the … More Dealing with Linkage Attacks using Differential Privacy
This blog post Sizing up the New Axis by Noah Smith that compares the combined economic strength of China and Russia against that of US and its key allies provides interesting insights into the robustness of the industrial base and manufacturing supply chains of the two blocs. On energy supply, which includes fossil fuels and … More A Short Look at Geoeconomics
It took a little while to write, but hopefully the following survey paper by Yang Li, Thilina Ranbaduge and yours truly can help demystify financial intelligence and privacy technologies for practitioners and technologists alike. The focus is on anti-money laundering and counter-terrorism financing, but the opportunity set is much broader. https://arxiv.org/abs/2408.09935 Here’s the abstract of … More Privacy Technologies for Financial Intelligence
Differential Privacy (DP) is, by now, the most widely adopted formal model of privacy protection used in industry [L23] and government [ABS22] but my sense is that its “semantics”, especially in the presence of correlated data and in the adversarial interactive setting, is still not broadly understood in the community, especially among practitioners. In the … More What Can Differential Privacy Actually Protect?
We have just released another paper on arXiv: https://arxiv.org/abs/2406.17649 Here’s the abstract: We consider the problem of privacy protection in Reinforcement Learning (RL) algorithms that operate over population processes, a practical but understudied setting that includes, for example, the control of epidemics in large populations of dynamically interacting individuals. In this setting, the RL algorithm … More Privacy-Preserving Reinforcement Learning for Population Processes
The Bretagnolle-Huber Inequality provides a bound on the total variation distance between two probability distributions in terms of their Kullback-Leibler divergence, and it is better than Pinsker’s Inequality when the KL divergence is larger than two, and it is never vacuous, as shown in this figure from [Canonne2023]. The following is an elementary proof, which … More Notes on the Bretagnolle-Huber Inequality
I have been incredibly frustrated with the lack of quality and content in many responsible AI (RAI) conversations. Almost all the (non-academic) RAI meetings I attended these past 12 months involve the speakers repeating words like fairness, accountability, and transparency basically for the entire duration of the meeting, with everyone nodding furiously in agreement about … More Improving the Quality of the Responsible AI Conversations
I have been thinking about data security issues, in particular database-reconstruction attacks. To quote Wikipedia, a reconstruction attack is any method for partially reconstructing a private database from public aggregate information. The question I am specifically interested in is this: Can an attacker with general interactive query access to a dataset recover a piece of … More How To Deal with Database Reconstruction Attacks
Mental Models 4 Life 