16.07.2020, ZAG : Rational curves on Enriques surfaces, but only few [Zoom Algebraic Geometry Seminar ] 08.07.2020, Johannes-Gutenberg-Universität Mainz : Arithmetik und Geometrie algebraischer Flächen 14.02.2020, Universität Hamburg: Arithmetik und Geometrie algebraischer Flächen 21.01.2020, University of Tokyo : (Few) rational curves on K3 surfaces [Algebraic Geometry Seminar] 31.10.2019, Universität Bielefeld: (Few) rational curves on K3 surfaces [Oberseminar Arithmetische Geometrie ] 18.06.2019, Universität Leipzig: Arithmetik und Geometrie algebraischer Flächen 12.06.2019, Institute of Mathematics, Polish Academy of Sciences, Krakow: Smooth rational curves on K3 surfaces 21.05.2019, Åbo University, Turku: Smooth rational curves on K3 surfaces [N-cube days X ] 20.01.2019, University of Tokyo: Equicharacteristic models of nodal Enrques surfaces [Workshop Arithmetic and Algebraic Geometry 2019 ] 12.09.2018, Cetraro: Lines on surfaces in IP^3 - from quartics to quintics [Conference Differential, Algebraic and Topological Methods in Complex Algebraic Geometry ] 11.07.2018, FBK, Trento: Zariski K3 surfaces [Workshop Recent Progress in the Arithmetic and Geometry of K3 Surfaces ] 15.06.2018, UFRJ, Rio: Singular K3 surfaces of class number 2 [Geometry seminar] 03.05.2018, Shepperton: Singular K3 surfaces of class number 2 [Mini-Conference K3 surfaces and Galois representations ] 26.04.2018, Pedagogical University, Krakow: Zariski K3 surfaces [Workshop and Conference Modern and Classical Aspects on Algebraic Surfaces ] 30.01.2018, Hosei University, Tokyo: Zariski K3 surfaces [Workshop Algebraic Geometry in Positive Characteristic and Related Topics] 07.12.2017, Universität Bayreuth: Elliptische Flächen 07.11.2017, University of Warwick: Zariski K3 surfaces [Warwick Algebraic Geometry Seminar ] 12.07.2017, Humboldt-Universität Berlin: Enriques surfaces with maximal root types: moduli and good reduction [Conference Higgs Bundles, K3 Surfaces and Moduli ] 22.06.2017, Uniwersytetu Jagiellońskiego, Krakow: Nodal curves and Enriques surfaces 02.06.2017, Universität Göttingen: Elliptic surfaces in geometry and arithmetic [Göttingen-Hannover Number Theory Workshop ] 30.03.2017, Haeundae, Korea: Configurations of nodal curves on Enriques surfaces [Algebraic Geometry Conference (Keum60)]13.12.2016, University of Tokyo: Singular K3 surfaces of class number 2 [Conference Arithmetic and Algebraic Geometry ]04.11.2016, Albert-Ludwigs-Universität Freiburg: Elliptic surfaces14.06.2016, Bedlewo: Gorenstein Q_l-cohomology projective planes [Conference: Varieties with trivial canonical bundles ]17.02.2016, Universität Saarbrücken: Geraden auf glatten Quartiken in IP^311.02.2016, FU Berlin: Lines on smooth quartics in IP^3 [Arithmetic Geometry Seminar ]04.02.2016, Universität Bielefeld: Eine glatte Quartik in IP^3 mit 60 Geraden und S_5-Symmetrie27.01.2016, Tokyo University: Gorenstein Q_l-cohomology fake projective planes [Conference Algebraic and Arithmetic Geometry 2016]17.12.2015, Gutenberg-Universität Mainz: Moduli of Gorenstein Q-homology fake projective planes [SFB-Kolloquium]02.12.2015, University of Cambridge: Moduli of Gorenstein Q-homology fake projective planes [Algebraic Geometry Seminar ]19.11.2015, KIAS, Seoul: Moduli of Gorenstein Q-homology fake projective planes [Conference on K3 surfaces and related topics ]19.10.2015, ICERM, Providence: Modularity of K3 surfaces and Calabi-Yau threefolds [Workshop Explicit methods for modularity of K3 surfaces and other higher weight motives] 29.01.2015, University of Tokyo: Profile of some beautiful K3 surfaces [Conference Algebraic and Arithmetic Geometry 2015 ]12.11.2014, Universität Bielefeld: Picard numbers — K3 surfaces and beyond2.07.2014, Universität Leipzig: K3 surfaces [Felix Klein Kolloquium]7.05.2014, Schiermonnikoog: The maximum number of lines on smooth quartic surfaces [Conference on K3 surfaces and their moduli ]25.03.2014, Leibniz Universität Hannover: From modularity to Maschke's octic and back [Workshop Experimental Methods in Computational Algebra]20.03.2014, LMU München: The maximum number of lines on smooth quartic surfaces [Workshop Geometry and Arithmetic of Surfaces ]17.02.2014, Universität Osnabrück: 64 lines on smooth quartic surfaces [Kolloquium ]27.01.2014 , Tokyo University : 64 lines on smooth quartic surfaces [Arithmetic and Algebraic Geometry 2014 ]13.11.2013, Fields Institute Toronto: 64 lines on smooth quartic surfaces [Thematic Program on Calabi-Yau Varieties ]12.11.2013, Fields Institute Toronto: Picard numbers of quintic surfaces [Thematic Program on Calabi-Yau Varieties ]29.01.2013, Tokyo University: Picard numbers of quintic surfaces [Arithmetic and Algebraic Geometry 2013 ]14.11.2012, Universität Rostock: Arithmetik von K3 Flächen [Mathematisches Kolloquium ] 9.11.2012, Universita degli studi di Milano: Picard numbers of quintic surfaces 12.09.2012, Leibniz Universität Hannover: Picard-Zahlen von Quintiken 30.06.2012, Krakow: Picard numbers of quintic surfaces [ECM satellite conference "Algebraic and Arithmetic Geometry" ] 30.05.2012, KU Leuven: Arithmetic of K3 surfaces 16.04.2012, Universität Zürich: Arithmetic of quintic surfaces [Oberseminar Algebraische Geometrie ] 16.01.2012, Institut für experimentelle Mathematik, Essen: Die Modularität von Maschkes Oktik und Calabi-Yau-Varietät 16.12.2011, Rijksuniversiteit Groningen: Arithmetic of quintic surfaces [Intercity Number Theory Seminar ] 08.12.2011, Freie Universität Berlin: Arithmetik algebraischer Flächen 06.12.2011, Humboldt Universität Berlin: Modularity of Maschke's octic and Calabi-Yau threefold [Forschungsseminar "Arithmetische Geometrie" ] 01.12.2011, Universität Augsburg: Arithmetik von K3-Flächen [Oberseminar ] 21.11.2011, Goethe-Universität Frankfurt Arithmetik von Quintiken [Kolloquium zur algebraischen Geometrie ] 10.10.2011, CIRM, Luminy: Shimura varieties for abelian fourfolds with an automorphism of order five [Conference on Moduli spaces and automorphic forms] 06.09.2011, Carl von Ossietzky Universität, Oldenburg: Sandwich-Theoreme für Shioda-Inose Strukturen [Oberseminar ] 16./17.08.2011, Fields Institute Toronto: Arithmetic of K3 surfaces [Workshop on Arithmetic and Geometry of K3 surfaces and Calabi-Yau threefolds ] 15.07.2011, Institut für experimentelle Mathematik, Essen: Arithmetik von Quintiken 08.07.2011, Universität Ulm: Arithmetik algebraischer Flächen 01.07.2011, Ruprecht-Karls-Universität Heidelberg: Shimura varieties for abelian fourfolds with an automorphism of order five [Hauptseminar Algebra und Zahlentheorie ] 14.04.2011, Universität Bonn/MPI: Shimura varieties for abelian fourfolds with an automorphism of order five [Seminar Algebraic Geometry] 31.03.2011, Uniwersytet Pedagogiczny, Krakow: Lines on Fermat surfaces 28.03.2011, Uniwersytetu Jagiellońskiego, Krakow: Shimura varieties for abelian fourfolds with an automorphism of order five 14.03.2011, Oslo University: Oversiktsforedrag over modularitet til Calabi-Yau variteter [Seminar in Algebra and Algebraic geometry ] 24.11.2010, Nagoya University: Lines on Fermat surfaces [Workshop Lattices, Reflection groups and Algebraic Geometry ] 18.11.2010, Technische Universität Darmstadt: Arithmetik und Geometrie algebraischer Flächen 29.10.2010, Lorentz Center, Leiden: Shimura varieties for abelian fourfolds with an automorphism of order five [Conference Arithmetic of Surfaces ] 30.09.2010, Copenhagen University: Lifts of projective congruence groups 29.09.2010, Copenhagen University: Noncongruence groups and modular forms 07.09.2010, Levico Terme, Italy: Arithmetic of singular Enriques surfaces [Conference Perspectives on Algebraic Varieties ] 16.08.2010, Universität Duisburg-Essen: Arithmetic of algebraic surfaces 01.06.2010, Universita' degli Studi di Milano: Arithmetic of Enriques surfaces [Algebraic Geometry Seminar Milano ] 21.05.2010, Goethe-Universität Frankfurt Modulformen und K3-Flächen 11.05.2010, Leibniz Universität Hannover Modularität und K3-Flächen [Antrittsvorlesung im Mathematisch-Physikalischen Kolloquium ] 23.04.2010, Utrecht University: Arithmetic of K3 surfaces [Dutch Mathematical Congress ] 08.03.2010, Hausdorff Institute, Bonn: Elliptic surfaces [Seminar: Algebra and Number Theory] 17.02.2010, Tokyo University: Non-liftable Calabi-Yau spaces [Algebraic Geometry in characteristic p and related topics ] 15.02.2010, Nagoya University: Enriques surfaces and jacobian elliptic K3 surfaces [Algebraic Geometry Seminar] 13.01.2010, Carl von Ossietzky Universität, Oldenburg: K3-Flächen und Modulformen [Colloquium ] 21.12.2009, Leibniz Universität Hannover: Calabi-Yau threefolds: fiber products of rational elliptic surfaces [Colloquium of the DFG graduate school 1463 ] 20.11.2009, Freie Universität, Berlin: Arithmetic of Enriques surfaces [NoGAGS] 17.11.2009, Universität Hamburg: K3 surfaces and modular forms [Colloquium for pure mathematics ] 30.09.2009, Harvard University: Arithmetic of Enriques surfaces [Number Theory Seminar] 10.09.2009, Chuo University, Tokyo: Lines on Fermat surfaces 02.09.2009, Rikkyo University, Tokyo: Arithmetic of Enriques surfaces [Workshop on K3, Enriques and Special Surfaces] 01.09.2009, Tokyo University: Arithmetic of K3 surfaces [Algebraic Geometry Seminar ] 12.06.2009, Heinrich-Heine-Universität, Düsseldorf: Arithmetik und Geometrie von K3 Flächen 17.04.2009, Utrecht: K3 surfaces and modular forms [Joint AKLS - InterCity seminar on modular forms in Utrecht ] 19.01.2009, Jussieu, Paris: K3 surfaces and modular forms [Seminaire de theorie des nombres de Chevaleret ] 01.12.2008, Banff, Canada: K3 surfaces and modular forms [Arithmetic of K3 surfaces ] 12.11.2008, KIAS, Seoul: K3 surfaces and modular forms [Algebraic Geometry in East Asia ] 06.11.2008, Nagoya University: Neron-Severi groups of surfaces in characteristic 0 and p [Algebraic Geometry in Positive Characteristics and Related Topics ] 31.10.2008, Hiroshima University: K3 surfaces and modular forms [Algebra seminar ] 14.10.2008, Humboldt Universität, Berlin: K3 surfaces and modular forms [Research seminar Algebraic Geometry ] 10.10.2008, University of Copenhagen: Surfaces with maximal Picard number [KU Number Theory Seminar] 23.09.2008, Leibniz Universität Hannover: Arithmetik von K3 Flächen 15.09.2008, Albert-Ludwigs Universität Freiburg: K3-Flächen und Modulformen 12.06.2008, Leibniz Universität Hannover: K3-Flächen vom Picard Rang 20 [Research Seminar Algebraic and Arithmetic Geometry ] 02.06.2008, Uniwersytetu Jagiellońskiego, Krakow: K3 surfaces and modular forms [Seminar on algebraic and analytic geometry] 18.03.2008, Queen's University, Kingston, ON: K3 surfaces of Picard rank 20 [Queen's Number Theory Seminar] 17.03.2008, Queen's University, Kingston, ON: Lines on Fermat surfaces [Queen's Algebraic Geometry Seminar ] 15.03.2008, Fields Institute, Toronto, ON: K3 surfaces and modular forms [Workshop on algebraic varieties ] 17.01.2008, Universität Duisburg-Essen: K3 surfaces and modular forms [Oberseminar Algebraische Geometrie Duisburg-Essen-Düsseldorf ] 12.01.2008, Courant Research Center Göttingen: K3 surfaces and modular forms [Courant-Colloquium ] 10.01.2008, Leibniz Universität Hannover: K3-Flächen und Modulformen [Research Seminar Algebraic and Arithmetic Geometry ] 18.12.2007, University of Copenhagen: K3 surfaces and modular forms [Copenhagen Mathematics Colloquium] 03.12.2007, MIT, Cambridge, MA: K3 surfaces of Picard rank 20 over Q [MIT STAGE ] 13.11.2007, MIT, Cambridge, MA: Calabi-Yau threefolds as fibre products of rational elliptic surfaces [Harvard/MIT algebraic geometry seminar ] 30.10.2007, Brandeis University, Waltham, MA: Singular K3 surfaces [Everytopic Seminar ] 13.09.2007, University of Texas, Austin, TX: Singular K3 surfaces [University of Texas - algebra, number theory and combinatorics seminar ] 06.09.2007, Rikkyo University, Tokyo: Singular K3 surfaces 29.08.2007, Nagoya University: Singular K3 surfaces and modular forms [Conference on Birational Automorphisms of Compact Complex Manifold and Dynamical Systems ] 16.08.2007, Queen's University, Kingston, ON: Singular K3 surfaces and modular forms 27.03.2007, Amherst College: Singular K3 surfaces [Amherst Five College Number Theory Seminar ] 26.02.2007, Boston University: Singular K3 surfaces [Boston University Algebra Seminar ] 08.02.2007, Georg-August-Universität Göttingen: Singuläre K3 Flächen [Events calendar of the mathematical faculty Göttingen (German) ]21.12.2006, Rheinische Friedrich-Wilhelms-Universität Bonn: Singular K3 surfaces [Bonn mathematics events calendar ]09.12.2006, CMS Winter 2006 Meeting: Classifying singular K3 surfaces [Session on Calabi-Yau Varieties and Mirror Symmetry ]14.11.2006, Rice University, Houston: Classifying singular K3 surfaces [Rice Algebraic Geometry Seminar ]24.10.2006, Harvard University: Classifying singular K3 surfaces [Harvard/MIT Algebraic Geometry Seminar ]21.10.2006, Fields Institute, Toronto: CM-modular forms and Calabi-Yau varieties [Workshop on Algebraic Varieties ]04.10.2006, Harvard University: CM newforms with rational coefficients [Harvard/ Number Theory Seminar ]08.07.2006, Lauenbrück Seminar: Elliptic modular surface for the commutator subgroup of SL(2,Z) 16.03.2006, Universita' degli Studi di Milano: Modularity of Calabi-Yau varieties [Number Theory Seminar Milano]02.02.2006, Universita' degli Studi di Milano: Calabi-Yau threefolds as fibre products of elliptic surfaces [Algebraic Geometry Seminar Milano ]20.12.2005, University Duisburg-Essen, Germany: Arithmetic of singular K3 surfaces and Hecke eigenforms [DFG-Research group "Arithmetic and Geometry" ]09.08.2005, AMS Summer Institute on Algebraic Geometry, University of Washington, Seattle, USA: Arithmetic of K3 surfaces [2005 AMS Summer Institute on Algebraic Geometry ]28.04.2005, University of Hannover, Germany: Hecke eigenforms with complex multiplication and rational coefficients [Oberseminar AKG Hannover ]18.03.2005, University of Groningen, Netherlands: Extremal elliptic K3 fibrations [Intercity number theory seminar ]25.11.2004, University of Hannover, Germany: Singular K3 Surfaces [Oberseminar AKG Hannover ]16.11.2004, University of Mainz, Germany: On the modularity of certain fibre products of the rational elliptic modular surface of level 5 [Gästeseite AG Mainz ]05.04.2004, University of Hannover, Germany: Modular Calabi-Yau threefolds arising from the modular elliptic surface of level 5 [AKG Miniworkshop ]23.03.2004, Duke University, Durham, NC, USA: New examples of modular rigid Calabi-Yau threefolds [Duke AG, Spring 2004 ]