# Calendar

Nov
20
Wed
Logic seminar: Sam Birns
Nov 20 @ 2:30 pm – 3:30 pm
Dec
11
Wed
Logic seminar: David Ross
Dec 11 @ 2:30 pm – 3:30 pm
Jan
31
Fri
Logic seminar: Jack Yoon
Jan 31 @ 2:30 pm – 3:30 pm

The first meeting of the logic seminar will be today at 2:30–3:20 in Keller 314. Our speaker will be Jack Yoon, who will give an introductory lecture on reverse mathematics. An abstract for his talk is below.

I will introduce the basics of reverse mathematics and begin Hunter’s paper on higher order reverse topology, which can be found here: https://www.math.wisc.edu/logic/theses/hunter.pdf

Reverse mathematics is a study of foundations of mathematics by assessing the “strength” of the theorems from ordinary mathematics. Rather than starting from given axioms to prove a theorem, it asks a reverse question “which axioms are necessary to prove the theorem?”. Traditionally, reverse mathematics has played out within the second order arithmetic, but further progress has been made on higher order systems as well. For example, Hunter’s paper above branches out to higher order systems to study the theorems of topology.

Feb
14
Fri
Logic seminar: David Webb
Feb 14 @ 2:30 pm – 3:30 pm

The logic seminar today will be given by David Webb. A title and abstract are below.

Title: On The Levin-V’yugin Degrees

Abstract: I will define and discuss the Levin-V’yugin degrees, a measure algebra defined on collections of reals closed under Turing equivalence. Roughly speaking, in this ordering collections A and B have that A<B if for any probabilistic algorithm, the probability that it produces an element of A that is not in B is 0. Time permitting, I will prove that the computable reals and the random reals each form an atom in this Boolean algebra, and discuss other degrees and their positions in the lattice.

The paper this talk is based on is here: https://arxiv.org/pdf/1907.07815.pdf

Feb
21
Fri
Logic seminar: David Webb (II)
Feb 21 @ 2:30 pm – 3:30 pm
Feb
28
Fri
Logic seminar: Umar Gaffar
Feb 28 @ 2:30 pm – 3:30 pm
Sep
14
Tue
Logic Seminar: Ellen Hughes
Sep 14 @ 10:30 am – 11:30 am

Time and place: Tuesday September 14, 10:30am in Holmes 247.

Speaker: Ellen Hughes, undergraduate student, UH Manoa.

Title: The interest equation in Lean

Abstract: We discuss how to solve the equation $y=x(1+i)^n$ for $i$ and for $n$ in the Lean proof assistant.
This is joint work with Monica Johnson, Ryan Sasaki and Prof. Kjos-Hanssen.

Covid-19 mitigation plan:
Participants will be required to show vaccination or testing status using the Lumisight app upon entry, observe 3ft social distancing, and to wear masks throughout.

Hope to see you there.

Sep
21
Tue
Logic seminar: David Webb
Sep 21 @ 10:30 am – 11:30 am

Title:
Computing from a pair of oracles one of which is useful