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BEGIN:VEVENT
SUMMARY:Jules Hedges (Max Planck Institute)
DTSTART;VALUE=DATE-TIME:20200415T170000Z
DTEND;VALUE=DATE-TIME:20200415T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/1
DESCRIPTION:Title: O
pen games: the long road to practical applications\nby Jules Hedges (M
ax Planck Institute) as part of ACT@UCR\n\n\nAbstract\nI will talk about o
pen games\, and the closely related concepts of lenses/optics and open lea
rners. My goal is to report on the successes and failures of an ongoing ef
fort to try to realise the often-claimed benefits of categories and compos
itionality in actual practice. I will introduce what little theory is need
ed along the way. Here are some things I plan to talk about:\n\n\n - Lenses as an abstraction of the chain rule
\n\n - Comb diagrams
\n\n - Surprising applications of open games: Bayesian inference\,
value function iteration
\n\n - The state of tool support
\n
\n - Open games in their natural habitat: microeconomics
\n\n -
Sociological aspects of working with economics
\n

\n
LOCATION:https://researchseminars.org/talk/ACTUCR/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Shulman (University of San Diego)
DTSTART;VALUE=DATE-TIME:20200422T170000Z
DTEND;VALUE=DATE-TIME:20200422T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/2
DESCRIPTION:Title: S
tar-autonomous envelopes\nby Michael Shulman (University of San Diego)
as part of ACT@UCR\n\n\nAbstract\nSymmetric monoidal categories with dual
s\, a.k.a. compact monoidal categories\, have a pleasing string diagram ca
lculus. In particular\, any compact monoidal category is closed with $[A\
,B] = (A^* \\otimes B)$\, and the transpose of $A \\otimes B \\to C$ to $A
\\to [B\,C]$ is represented by simply bending a string. Unfortunately\,
a closed symmetric monoidal category cannot even be embedded fully-faithfu
lly into a compact one unless it is traced\; and while string diagram calc
uli for closed monoidal categories have been proposed\, they are more comp
licated\, e.g. with "clasps" and "bubbles". In this talk we obtain a stri
ng diagram calculus for closed symmetric monoidal categories that looks al
most like the compact case\, by fully embedding any such category in a sta
r-autonomous one (via a functor that preserves the closed structure) and u
sing the known string diagram calculus for star-autonomous categories. No
knowledge of star-autonomous categories will be assumed.\n
LOCATION:https://researchseminars.org/talk/ACTUCR/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gershom Bazerman
DTSTART;VALUE=DATE-TIME:20200429T170000Z
DTEND;VALUE=DATE-TIME:20200429T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/3
DESCRIPTION:Title: A
localic approach to the semantics of dependency\, conflict\, and concurre
ncy\nby Gershom Bazerman as part of ACT@UCR\n\n\nAbstract\nPetri nets
have been of interest to applied category theory for some time. Back in th
e 1980s\, one approach to their semantics was given by algebraic gadgets c
alled "event structures." We use classical techniques from order theory to
study event structures without conflict restrictions (which we term "depe
ndency structures with choice") by their associated "traces"\, which let u
s establish a one-to-one correspondence between DSCs and a certain class o
f locales. These locales have an internal logic of reachability\, which ca
n be equipped with "versioning" modalities that let us abstract away certa
in unnecessary detail from an underlying DSC. With this in hand we can giv
e a general notion of what it means to "solve a dependency problem" and co
mbinatorial results bounding the complexity of this. Time permitting\, I w
ill sketch work-in-progress which hopes to equip these locales with a noti
on of conflict\, letting us capture the full semantics of general event st
ructures in the form of homological data\, thus providing one avenue to th
e topological semantics of concurrent systems. This is joint work with Ray
mond Puzio.\n
LOCATION:https://researchseminars.org/talk/ACTUCR/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sarah Rovner-Frydman (Marlboro College)
DTSTART;VALUE=DATE-TIME:20200506T170000Z
DTEND;VALUE=DATE-TIME:20200506T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/4
DESCRIPTION:Title: S
eparation logic through a new lens\nby Sarah Rovner-Frydman (Marlboro
College) as part of ACT@UCR\n\n\nAbstract\nSeparation logic aims to reason
compositionally about the behavior of programs that manipulate shared res
ources. When working with separation logic\, it is often necessary to mani
pulate information about program state in patterns of deconstruction and r
econstruction. This achieves a kind of "focusing" effect which is somewhat
reminiscent of using optics in a functional programming language. We make
this analogy precise by showing that several interrelated techniques in t
he literature for managing these patterns of manipulation can be derived a
s instances of the general definition of profunctor optics. In doing so\,
we specialize the machinery of profunctor optics from categories to posets
and to sets. This simplification makes most of this machinery look more f
amiliar\, and it reveals that much of it was already hiding in separation
logic in plain sight.\n
LOCATION:https://researchseminars.org/talk/ACTUCR/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tai-Danae Bradley (CUNY Graduate Center)
DTSTART;VALUE=DATE-TIME:20200513T170000Z
DTEND;VALUE=DATE-TIME:20200513T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/5
DESCRIPTION:Title: F
ormal concepts vs. eigenvectors of density operators\nby Tai-Danae Bra
dley (CUNY Graduate Center) as part of ACT@UCR\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ACTUCR/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gordon Plotkin (University of Edinburgh)
DTSTART;VALUE=DATE-TIME:20200520T170000Z
DTEND;VALUE=DATE-TIME:20200520T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/6
DESCRIPTION:Title: A
complete axiomatisation of partial differentiation\nby Gordon Plotkin
(University of Edinburgh) as part of ACT@UCR\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/ACTUCR/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nina Otter (UCLA)
DTSTART;VALUE=DATE-TIME:20200603T170000Z
DTEND;VALUE=DATE-TIME:20200603T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/7
DESCRIPTION:Title: V
alues and inclusivity in the Applied Category Theory community\nby Nin
a Otter (UCLA) as part of ACT@UCR\n\n\nAbstract\nSaddened by the current e
vents\, we are taking this opportunity to pause and reflect on what we can
do to change the status quo and try to bring about real and long-lasting
change. \n\nThus\, we are holding a discussion aimed at finding concrete s
olutions to make the Applied Category Theory community more inclusive\, an
d also to reflect about the values that our community would like to stand
for and endorse\, in particular\, in terms of which sources of funding go
against our values. While this discussion is specific to the applied categ
ory theory community\, we believe that many of the topics will be of inter
est also to people in other fields\, and thus we welcome anybody with an i
nterest to attend. The discussion will consist of two parts: we will have
first several people give short talks to discuss common issues that we nee
d to address\, as well as present specific plans for initiatives that we c
ould take. We believe that the current pandemic\, and the fact that all ac
tivities are now taking place remotely\, gives us the opportunity to invol
ve people who would otherwise find it difficult to travel\, because of dis
abilities\, financial reasons or care-taking responsibilities. Thus\, now
we have the opportunity to come up with new types of mentoring\, collabora
tions\, and many other initiatives that might have been difficult to envis
ion until just a couple of months ago. The second part of the discussion w
ill take place on the category theory community server\, and its purpose i
s to allow for a broader participation in the discussion\, and ideally dur
ing this part we will be able to flesh out in detail the specific initiati
ves that have been proposed in the talks.\n
LOCATION:https://researchseminars.org/talk/ACTUCR/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Prakash Panangaden (McGill)
DTSTART;VALUE=DATE-TIME:20200408T170000Z
DTEND;VALUE=DATE-TIME:20200408T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/8
DESCRIPTION:Title: A
categorical view of conditional expectation\nby Prakash Panangaden (M
cGill) as part of ACT@UCR\n\n\nAbstract\nThis talk is a fragment from a la
rger work on approximating Markov processes. I will focus on a functorial
definition of conditional expectation without talking about how it was use
d. We define categories of cones---which are abstract versions of the fami
liar cones in vector spaces---of measures and related categories cones of
Lₚ functions. We will state a number of dualities and isomorphisms betwe
en these categories. Then we will define conditional expectation by exploi
ting these dualities: it will turn out that we can define conditional expe
ctation with respect to certain morphisms. These generalize the standard n
otion of conditioning with respect to a sub-sigma algebra. Why did I use t
he plural? Because it turns out that there are two kinds of conditional ex
pectation\, one of which looks like a left adjoint (in the matrix sense no
t the categorical sense) and the other looks like a right adjoint. I will
review concepts like image measure\, Radon-Nikodym derivatives and the tra
ditional definition of conditional expectation. This is joint work with Ph
ilippe Chaput\, Vincent Danos and Gordon Plotkin. \n
LOCATION:https://researchseminars.org/talk/ACTUCR/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simon Willerton (University of Sheffield)
DTSTART;VALUE=DATE-TIME:20200527T170000Z
DTEND;VALUE=DATE-TIME:20200527T180000Z
DTSTAMP;VALUE=DATE-TIME:20241016T073417Z
UID:ACTUCR/9
DESCRIPTION:Title: T
he Legendre–Fenchel transform from a category theoretic perspective\
nby Simon Willerton (University of Sheffield) as part of ACT@UCR\n\nAbstra
ct: TBA\n
LOCATION:https://researchseminars.org/talk/ACTUCR/9/
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