synthetic differential geometry
Introductions
from point-set topology to differentiable manifolds
geometry of physics: coordinate systems, smooth spaces, manifolds, smooth homotopy types, supergeometry
Differentials
Tangency
The magic algebraic facts
Theorems
Axiomatics
(shape modality $\dashv$ flat modality $\dashv$ sharp modality)
$(ʃ \dashv \flat \dashv \sharp )$
dR-shape modality $\dashv$ dR-flat modality
$ʃ_{dR} \dashv \flat_{dR}$
(reduction modality $\dashv$ infinitesimal shape modality $\dashv$ infinitesimal flat modality)
$(\Re \dashv \Im \dashv \&)$
fermionic modality $\dashv$ bosonic modality $\dashv$ rheonomy modality
$(\rightrightarrows \dashv \rightsquigarrow \dashv Rh)$
Models
Models for Smooth Infinitesimal Analysis
smooth algebra ($C^\infty$-ring)
differential equations, variational calculus
Chern-Weil theory, ∞-Chern-Weil theory
Cartan geometry (super, higher)
The term spin connection is traditionally used in physics – for instance in first-order formulation of gravity – to denote a connection on the tangent bundle of a manifold with spin structure given as a special orthogonal Lie algebra-valued connection on the underlying special orthogonal group-principal bundle. The term is mainly used to distinguish from the the connection expressed in Christoffel symbols. Since for this connection alone the spin structure is not important, the term spin connection is often used for $\mathfrak{so}$-connecition on any orientable manifold.
See at field (physics) the section Ordinary gravity.