Formalized Metatheory with Terms Represented by an Indexed Family of Types -- A Content Based Mathematical Search Engine: Whelp -- A Machine-Checked Formalization of the Random Oracle Model -- Extracting a Normalization Algorithm in Isabelle/HOL -- A Structured Approach to Proving Compiler Optimizations Based on Dataflow Analysis -- Formalising Bitonic Sort in Type Theory -- A Semi-reflexive Tactic for (Sub-)Equational Reasoning -- A Uniform and Certified Approach for Two Static Analyses -- Solving Two Problems in General Topology Via Types -- A Tool for Automated Theorem Proving in Agda -- Surreal Numbers in Coq -- A Few Constructions on Constructors -- Tactic-Based Optimized Compilation of Functional Programs -- Interfaces as Games, Programs as Strategies -- ?Z: Zermelo's Set Theory as a PTS with 4 Sorts -- Exploring the Regular Tree Types -- On Constructive Existence.