Rohit Parikh wrote a beautiful eulogy for Horacio Arló-Costa, which I post here with his permission:
On July 11, the TARK XIII conference gave a party in Groningen for the attendees. Afterwards, Horacio and I had a small dinner in a plaza in Groningen. Only two weeks have passed and he is already gone.
But he will be honored by various events at Columbia, at CMU and most likely also in Munich and in Buenos Aires.
For me, he was a student who became an affectionate and long standing friend. We met each other frequently in New York, where he gave several talks at CUNY. But we also met in Pittsburgh, Florence (where he introduced me to Vann McGee), and of course in Groningen. He knew my family and I knew his wife Claudia.
Horacio was a person of immense scholarly integrity and an ability to produce impressive original research. He was surely a world expert in the foundations of probability and aspects of conditionals and modal logic. It was quite frequent for me to ask him a question and get an instant answer. Some have said he was a walking encyclopedia. This is a fair assessment.
He shared my interest in Borges (or perhaps I shared his), in Tagore and in Blake. There was a deep spiritual sense in him, which apparently his father also had and which he celebrated in his eulogy to his late father. I read part of the same eulogy at Horacio’s funeral in Westchester. What Horacio said about his father, in large part, applied also to Horacio himself.
I am sure his work will be carried on by others, especially his student Arthur Paul Pedersen. I look forward to being in touch with Paul, with Horacio’s colleagues at CMU and his many friends at Columbia.