Masterclass by Dominic Joyce and Yuuji Tanaka from Oxford University 6-15 August 2018

Title: Riemannian holonomy groups & Gauge theory and instanton moduli spaces

2018.01.25 | Christine Dilling

Date Mon 06 Aug Wed 15 Aug
Time 09:30    12:00
Location Aud D2 (1531-119)

Not open yet  

Dominic Joyce (Oxford University)

Title: Riemannian holonomy groups

Abstract: Let (X, g) be a connected, simply-connected Riemannian n-manifold. The holonomy group Hol(g) is a subgroup of SO(n) which measures the tensors T on X constant under the Levi-Civita connection ∇ of g. Berger (1955) showed that if g is irreducible and nonsymmetric then Hol(g) is one of:

(i) SO(n) (the boring case, for generic g);
(ii) U(m) for n=2m (Kähler metrics);
(iii) SU(m) for n=2m (Calabi-Yau metrics);
(iv) Sp(m) for n=4m (hyperkähler metrics);
(v) Sp(m)Sp(1) for n=4m (quaternionic Kähler metrics);
(vi) G2 for n=7 and (vii) Spin(7) for n=8 (exceptional holonomy)

Each of classes (ii)-(vii) have their own interesting geometry. We will review the theory of holonomy groups and Berger’s classification, and discuss Riemannian manifolds in classes (ii)-(vii), especially compact manifolds. If time allows we will also discuss calibrated submanifolds, distinguished classes of minimal submanifolds in Riemannian manifolds with special holonomy.

Yuuji Tanaka (Oxford University)

Title: Gauge theory and instanton moduli spaces

Abstract: Let (X, g) be a compact Riemannian manifold, usually with some additional structure (e.g. g may have special holomomy), and E → X be a vector bundle or principal bundle, and ∇ be a connection on E, with curvature F. We call (E,∇) an instanton if F satisfies a linear equation depending on g and the additional structure. Gauge theory is the study of moduli spaces M of instantons, that is, M is the set of isomorphism classes of instantons (E,∇), equipped with a geometric structure which reflects how instantons vary in families.

In good cases, M is a smooth manifold, which can be compactified by adding a ‘boundary’ of singular instantons. Instanton moduli spaces may contain interesting information about (X, g).

Gauge theory was invented in Physics, but became important in Mathematics because of Donaldson theory of 4-manifolds, which used instanton moduli spaces to define invariants which could distinguish different smooth structures on the same topological 4-manifold. Gauge theory is connected to Riemannian holonomy, as there are interesting instanton-type equations on manifolds (X, g) with holonomy SO(3), SO(4), U(m), SU(3), SU(4), G2 and Spin(7). Higherdimensional gauge theory (dim > 4) is the focus of much current research.

Topics will include: basics of gauge theory; moduli spaces of instantons on 4- manifolds, the Uhlenbeck compactification and Donaldson theory; holomorphic vector bundles on Kähler manifolds, Hermitian-Einstein connections and the Hitchin-Kobayashi correspondence; G2 and Spin(7) instantons; and compactifying instanton moduli spaces in higher dimensions. 

Preliminary time table

Location: Aud D2 (1531-119)

Monday 6th – Friday 10th August and Monday 13th – Tuesday 14th August 
09:30-09:45: Coffee and check-in
09.45-10.30: Dominic Joyce
10.45-11.30: Dominic Joyce
11.40-12.00: Q+A's
12.00-13.30: lunch
13.30-14.15: Yuuji Tanaka
14.30-15.15: Yuuji Tanaka
15.30-15.50: Q+A's. 

Wednesday 15th August
09.30-10.15: Dominic Joyce
10.15-10.30: Yuuji Tanaka
11.30-12.00: Q+A's 
12.00 Masterclass finishes and lunch

List of participants
Will be updated regularly 

Organizing committee
Jørgen Ellegaard Andersen (Aarhus University, Denmark)   
Dominic Joyce (Oxford University)
Yuuji Tanaka (Oxford University) 

Questions? Please send an e-mail to 

Video recordings will be available after the masterclass here

Master Class