A Bridge between CSP Processes and Functional Automata B Ballenghien B Wolff In HOL-CSP, defines Proc-Omata from functional automata, in four variants: whether deterministic/terminating or not. We do the Dining Philosophers for any number finite of diners. www.isa-afp.org/entries/HOL-...

Parameterized Termination for Sequential Composition and Synchronization Product B Ballenghien Building on HOL-CSP we introduce versions of these operators that with parameterized termination. We establish algebraic and operational laws, and fundamental properties. www.isa-afp.org/entries/HOL-...

'Sets' Revisited: Working with a Large Category in Isabelle/HOL EW Stark We formalise the category of sets and functions and prove standard properties. Key is an axiom that allows us to obtain objects internal to the category corresponding to externally given sets. www.isa-afp.org/entries/Sets...

The Impossibility of Strategyproof Rank Aggregation M Eberl, P Lederer In Social Choice Theory, a social welfare function (SWF) maps a collection of individual preferences to an aggregated preference relation. This entry contains two impossibility results for SWFs. www.isa-afp.org/entries/SWF_...

A modern-day tragedy, BUT YOU CAN HELP. 1 Like = 1 Pray 1 Share = 10,000 Prays

Linear orders as rankings M Eberl Formalises the isomorphism between finite linear orders and lists, where the list is interpreted as a ranking: it lists the elements in strictly descending order. It also provides an algorithm to compute topological sortings. www.isa-afp.org/entries/Rank...

Swap Distance M Eberl The swap distance between 2 lists is the minimum # of swaps of adjacent elements needed to make the two lists the same. An O(n log n) algorithm for it is given via the connection to the number of inversions of a list, already available in the AFP www.isa-afp.org/entries/Swap...

PV solar panels produce about 20x more usable energy per hectare of land than growing biofuels ourworldindata.org/biofuel-land...

New in the AFP: Abel's Limit Theorem Kangfeng Ye This mechanises Abel's limit theorem on power series with real coefficients. An application of this theorem extends the generalised binomial theorem for a specific example from (-1,1) to its boundary cases –1 and 1. www.isa-afp.org/entries/Abel...

Isn't this a telling aspiration? To want robots to look after your kids, so you can do stuff, rather than robots to do stuff, so you can spend time with your kids? The darkness inside these shrivelled men must be like a gaping unfillable void.

@gilesyb.bsky.social this is what the inflection point looks like - chinas emissions will be tanking very soon e360.yale.edu/digest/china...

Compressed Oracles D Unruh We formalize the compressed quantum random oracle methodology by Zhandry (Crypto 2019). This is a formalism for modeling quantum random oracles to make quantum cryptographic proofs feasible. See Unruh (arXiv 2021). www.isa-afp.org/entries/Comp...

Nice to see it in real life

New on my blog: Broken proofs and broken provers lawrencecpaulson.github.io/2026/01/15/B...

Set Reconciliation P Hofmeier, E Karayel This entry verifies the set reconciliation algorithm with nearly optimal communication complexity, due to Minsky et al. Two partners who have a similar pair of sets can reconcile them using messages of nearly optimal size. www.isa-afp.org/entries/Set_...

Dynamic Pushdown Networks P Lammich A formalization of Dynamic Pushdown Networks (DPNs) and the automata-based algorithm for computing backward reachability sets using Isabelle/HOL. DPNs are an abstract model for interprocedural programs with dynamic thread creation. www.isa-afp.org/entries/Dyna...

The Partition Function and the Pentagonal Number Theorem Manuel Eberl The partition function gives the number of ways to write an integer as a sum of positive integers, not taking order into account. I use the Jacobi Triple Product to prove Pentagonal Number Theorem. www.isa-afp.org/entries/Pent...

Typed Ordered Resolution by A A Ahmed, B Toth Ordered Resolution is a refutationally complete calculus for first-order logic, used in many automatic theorem provers, which works by saturating a set of clauses. This entry includes a clean completeness proof. www.isa-afp.org/entries/Type...

New in the AFP: Dedekind Sums by Manuel Eberl, Anthony Bordg, Lawrence C Paulson and Wenda Li The formalisation follows Chapter 3 of Apostol's Modular Functions and Dirichlet Series in Number Theory and contains all facts related to Dedekind sums from it. www.isa-afp.org/entries/Dede...

From a focus group of Gen Z Republicans. (www.city-journal.org/article/manh...) Tell me again about how Zohran Mamdani is the big threat to Jewish thriving in the US today.

Important to note Maples denies saying it. People will have to judge who they believe, but worth noting some sources really did not want to go on the record because they feared retribution. The idea that people are doing this for attention seems unlikely given the type of attention they will get.

Isabelle2025-1 is now available, offering e.g. * PIDE: load markup from background session image (e.g. theory "HOL.Nat"). * Isabelle/jEdit: support for command-line system options ("-o"). www.cl.cam.ac.uk/research/hvg... isabelle.in.tum.de

Regarding the AWS separation kernel verification project, the YouTube video I shared earlier has been replaced by an improved version at a different URL (see comments)

Now on youTube: an overview of the AWS Nitro architecture, the new separation kernel (Nitro Isolation Engine) and the verification effort. It is aimed at a general audience but a few Isabelle details can be spotted. youtu.be/b0P55gHhG4g

I want this for Christmas, preferably built into my specs! I’m sure it will happen at some time!

New on my blog: 50 years of proof assistants lawrencecpaulson.github.io/2025/12/05/H...

Not a fan of excessive gnome-age, but I will die for their right to piss off the neighbours so much that they end up in the Daily Telegraph. www.telegraph.co.uk/gift/c58f3e2...

The UK, where the day after a decision to take half a million children out of poverty, the media & political world has been full of sneering at those same children & their families, labelling them as ‘Benefits Street’, while the same people are moaning about a tax on £2m mansions. Shameful stuff.

Just out: Functional Data Structures, edited by Tobias Nipkow

The Weak Spectroscopy Game to Characterize Behavioral Equivalences Lisa Barthel et al We formalise Bisping and Jansen's weak spectroscopy game, which can be used to characterize and decide a hierarchy of behavioral equivalences for systems with internal behavior. www.isa-afp.org/entries/Weak...

Rely-Guarantee Extensions and Locks RJ Colvin et al We extend the existing rely-guarantee library with flexible syntax, data-invariant support, etc. We apply our library to three queue locks: the Abstract Queue Lock, the Ticket Lock, and the Circular Buffer Lock. www.isa-afp.org/entries/RG_L...