We had a celebration of Gordon Plotkin's eightieth birthday today, featuring many interesting talks. It's hard not to run into Gordon's work if you do anything involving semantics or concurrency or programming languages. My favourite talk of the day was probably my friend Ningning Xie's talk, but I also enjoyed Rob van Glabbeek's talk on his Justness work.

My only major Gordon anecdote is that he was on my interview panel when I interviewed for the job at the University of Edinburgh, and I was astounded to realise that not only was he still alive, but also he somehow didn't appear much older than any of the famous pictures of him.

So, congratulations and happy birthday to the timeless Gordon Plotkin, a huge contributor to our field and an intellectual hero to many of us.

We had a celebration of 40 years since the foundation of the Laboratory for Foundations of Computer Science (LFCS) by Robin Milner, Rod Burstall and Gordon Plotkin today. This was the institute that I was (and in some sense, remain) part of at the University of Edinburgh. I don't have much time for navel-gazing, and sadly most of the technical talks were either well outside my area, a demonstration of how brain-poisoned by LLMs my former Edinburgh colleagues have become, or both. I didn't really get much out of the day.

I am still glad to be here in Edinburgh for this week, though. It's great to catch up with some old friends.

While his birthday was back in April, to fit with Plotkin 80 and LFCS 40, we had a birthday event for Philip Wadler today, celebrating his 70th year.

I really loved Conor's talk on dependent session types, which was inspired by a question from Phil ten years earlier at his 60th birthday event. Her proposed design resembles Peter Hancock's interaction structures quite a bit. Very nice work.

I also gave my talk, which I peppered with many anecdotes about meeting Phil. I got a lot of interest about potentially using Holbert-ng, including from Marcelo Fiore among others. Very exciting stuff!

There was a big movement of "community singing" in the UK during the 1920s (mostly pushed by tory rags). They commissioned Novello and similar music publishers to make score compilations to support community sing-alongs. Today while charity shop perusing, I managed to get the Daily Express compilation (edited by John Goss!) and the News Chronicle compilation, and had a read through. Lots of scottish airs, some hymns and carols, a few american spirituals and folk songs, sea shanties and some British patriotic songs. Interesting charity shop find!

The expanded version of our 2024 paper has finally been published in the journal Information and Computation. This paper includes some of the work that lays the foundation for what I'm now doing with Kai Phan.

Da pacem Dómine, sustinéntibus te, ut prophétæ tui fidéles inveniántur: exáudi preces servi tui, et plebis tuæ Israel.

I sang again at St. Michael and all Saints in the morning where we sang Palestrina's Missa Brevis and Wesley's Wash me throughly:

Wash me throughly from my wickedness

And forgive me all my sin

For I acknowledge my faults

And my sin is ever before me

I also joined the choir at Old St. Paul's once again for Evensong and Benediction. We sang canticles by Harold Darke (both Magnificat and Nunc Dimittis), and an anthem by our own John Kitchen: Stand, Holy Cross, a setting of a text by Gordon Graham (link is to the livestream of the service):

Stand, Holy Cross, between my God and me

And cast a shadow where my heart can hide

Its frail mortality

From his perspicuous light.

The Cross's shade supplies my sin's disguise.

My soul protected, I can turn my eyes;

And now the Father’s light allows me view:

A world, my world, made new.

Then as horizons widen to a farther shore

And light on light enlightens more and more,

This larger vision brings a deeper peace

And sin and sorrow cease.

Stand, Holy Cross, between my God and me.