add Adrian; add Harry's talk details

content/lsd-seminar/2023fa.md

@@ -21,8 +21,8 @@ Talks will be advertised on the [ucsc-lsd-seminar-announce](https://groups.googl
 |-------              |---------                                                              |---------                                                          |
 | [Sept. 29](#sept-29)| Vikram Narayanan                                                      | Towards fine-grained compartmentalization of operating system kernels |
 | [Oct. 6](#oct-6)    | Nick Rioux                                                            | Compositional & Scalable Programming in Granite                   |
-| [Oct. 13](#oct-13)  | Harrison Goldstein                                                    | TBD                                                               |
-| [Oct. 20](#oct-20)  | TBD                                                                   | TBD                                                               |
+| [Oct. 13](#oct-13)  | Harrison Goldstein                                                    | Advancing Property-Based Testing in Theory and Practice           |
+| [Oct. 20](#oct-20)  | Adrian Lehmann                                                        | TBD                                                               |
 | [Oct. 27](#oct-27)  | Elaine Li                                                             | TBD                                                               |
 | [Nov. 3](#nov-3)    | Karine Even-Mendoza                                                   | TBD                                                               |
 | [Nov. 17](#nov-17)  | Suha S. Hussain                                                       | TBD                                                               |
@@ -93,15 +93,36 @@ programs across a distributed system.
 
 **Speaker:** Harrison Goldstein
 
-**Title:** TBD
-
-**Abstract:** TBD
-
-**Bio:** TBD
+**Title:** Advancing Property-Based Testing in Theory and Practice
+
+**Abstract:** Property-based testing (PBT) is a testing methodology that allows users to write executable
+specifications of programs and test those specifications with automatically generated program
+inputs. PBT is well-documented as a power-tool for bug-finding, with success stories at companies
+like DropBox, Volvo, and Amazon, but we think it has still not reached its full potential. Our group
+has taken a user-centered approach to advancing PBT, talking to real developers and discovering the
+challenges that they face when using it.
+
+I present two new abstractions for random data generators---free generators and reflective
+generators---that help address some of these challenges. Free generators re-imagine generators as
+"parsers of randomness." They show that a generator is really a parser for sequences of random
+choices, and this perspective suggests new generation techniques. Reflective generators build on
+free generators, adding support for "backward" execution in which a generated value can be turned
+back into the sequence of choices that produced it. Backward generator execution is the foundation
+for a wealth of new algorithms, including ones for test-case "shrinking," test-case mutation, and
+example-based generator tuning.
+
+Moving forward, we plan to focus on usability: free and reflective generators should be easy for
+developers to write, and they should make other parts of the PBT process easier as well. I discuss
+future work in this direction.
+
+**Bio:** Harry Goldstein is a Ph.D. candidate at the University of Pennsylvania, advised by professor
+Benjamin Pierce. His work leverages techniques from both programming languages and human-computer
+interaction to make tools for software testing more powerful and usable. You can find his
+publication list, blog, and other information at https://harrisongoldste.in.
 
 # Oct. 20
 
-**Speaker:** TBD
+**Speaker:** Adrian Lehmann
 
 **Title:** TBD