One of my recent academic projects has been to thoroughly read all of Janina Hosiasson’s published works. It is not a trivial task, and I believe that no one has actually done it (recently anyways). First, there are of course language barriers: she wrote and published in four languages. Second, there are issues of time and space: some of her articles happen to be in by now very obscure journals, magazines, and conference proceedings – not available digitally, and in some cases available only in a handful of hard copies.

One of the articles that I was missing in my personal collection was “Quelques remarques sur la dépendance des probabilités a posteriori de celles a priori.” It was a paper based on a talk given at a congress of mathematicians from Slavic countries in 1929 in Warsaw.

I found a copy of the proceedings of the congress in the philosophy library at the University of Warsaw. Last January I had the opportunity to drop in to Warsaw for a day and check out the book. At the first glance, it looked as boring as any other volume of conference proceedings. I may be a sucker for old pieces of paper, but even I have my limits.

But wait, what is that pencil note in the corner of the inside cover?

It is in Janina’s own handwriting! And it says: “from Janina Hosiasson.” She donated her own copy of the proceedings to the library in the department. Her own thesis did not make it through the war; none of her belongings did. But this one book, it did. And it is still at that library.

A true Warsaw logician that she was, she could not help but to correct her own paper in print:

It is something that I have seen before, that level of attention to detail. In 1940, while barely making a living as a refugee in Lithuania and desperately fighting for a visa to get out, she would still write anxious letters to Tarski about how she discovered a mistake in one of the proofs in her paper on confirmation and would he please make sure that the corrections are taken in. She also compiled a whole list of errata for her analogy paper – a list that did not even leave Lithuania, it seems. None of those corrections were applied to the printed material. But at least that one hard copy in the Warsaw library is perfect now, and forever will be.