Subject: categories: Alfred Sober - some recollections

From: [email-masked] (Steven Vickers)
Date: Mon, 20 Jul 1998 16:09:15 +0000

Recent mention of sober spaces brought to mind memories of Alfred Philpott
Sober, whose sad death from liver failure five years ago ended a long
career in topology. Though largely unpublished, it was his work that
underlay the notion of what are now known as sober spaces.

In Sober's view, points of topological spaces are essentially blurred and
hazy: however hard you try to focus on them they always seem to jiggle
about a bit - to him "focusing on a point" meant to find it within some
_open_ neighbourhood, and these almost always left some room for manoeuvre.
He understood the points to be exactly their open neighbourhood filters,
and the spaces that would now be called non-sober were trying to impose an
over-clear view of reality, making artificial distinctions between what was
actually the same thing or trying to deny the existence of something he
could see with his own eyes.

On the related subject of continuity, he saw its essence as that of a
function was that was not unduly upset by this jiggling: as long as the
argument didn't jiggle too much, the result wouldn't either, and he liked
to demonstrate the idea by carrying a tray of drinks across a crowded room.

Though not one of the founders of locale theory, he was aware of the idea
and greatly sympathetic to it - though he couldn't see any reason for using
the French spelling and pronunciation. Once when in the midst of explaining
his ideas the lattice structures started to become manifest and he would
excitedly talk about "getting down to the local".

He studied initially at Cambridge under the influence of Charles Wells (the
Bedford Charles Wells, NOT the well-known category theorist) and his
thesis, starting off on Klein bottles, soon took in Gross bottles too. He
made his academic home in the University of Portsmouth and was much loved
by both his colleagues and his students for his parties and for his
never-failing warm welcome "Come in and what'll you have?" He is much
missed by all who knew him.

Steve Vickers.