Speaker: Andrew Harder. Date: 10:30 14/08/2020 Title: Calabi-Yau threefolds fibered by K3 surfaces and their internal Picard-Fuchs equation Abstract: A K3 fibered Calabi-Yau threefold is a Calabi-Yau threefold which admits a proper morphism to the projective line whose smooth fibers are K3 surfaces. It is known that many interesting families of Calabi-Yau threefolds admit K3 surface fibrations, but since the moduli space of K3 surfaces is quite large, a full classification of K3 fibered Calabi-Yau threefolds is likely out of our grasp. However, if we impose the condition that the K3 surface fibers have Picard rank 19, then the question of classification becomes much easier, and familiar features from the theory of elliptic surfaces begin to appear. In this talk, I will discuss some aspects of the classification of Calabi-Yau threefolds fibred by K3 surfaces of Picard rank 19, focusing on the role played by Picard-Fuchs equations. This is joint work with C. Doran, A. Novoseltsev, and A. Thompson.