BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Jules Hedges (Max Planck Institute) DTSTART:20200415T170000Z DTEND:20200415T180000Z DTSTAMP:20260422T225755Z 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 LOCATION:https://researchseminars.org/talk/ACTUCR/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Michael Shulman (University of San Diego) DTSTART:20200422T170000Z DTEND:20200422T180000Z DTSTAMP:20260422T225755Z 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:20200429T170000Z DTEND:20200429T180000Z DTSTAMP:20260422T225755Z 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:20200506T170000Z DTEND:20200506T180000Z DTSTAMP:20260422T225755Z 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:20200513T170000Z DTEND:20200513T180000Z DTSTAMP:20260422T225755Z 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:20200520T170000Z DTEND:20200520T180000Z DTSTAMP:20260422T225755Z 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:20200603T170000Z DTEND:20200603T180000Z DTSTAMP:20260422T225755Z 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:20200408T170000Z DTEND:20200408T180000Z DTSTAMP:20260422T225755Z 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:20200527T170000Z DTEND:20200527T180000Z DTSTAMP:20260422T225755Z 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/ END:VEVENT END:VCALENDAR