@article{BaerBecker2014,
  author    = {B{\"a}r, Christian and Becker, Christian},
  title     = {Differential characters and geometric chains},
  series = {Lecture notes in mathematics : a collection of informal reports and seminars},
  volume    = {2112},
  journal   = {Lecture notes in mathematics : a collection of informal reports and seminars},
  publisher = {Springer},
  address   = {Berlin},
  isbn      = {978-3-319-07034-6; 978-3-319-07033-9},
  issn      = {0075-8434},
  doi       = {10.1007/978-3-319-07034-6_1},
  pages     = {1 -- 90},
  year      = {2014},
  abstract  = {We study Cheeger-Simons differential characters and provide geometric descriptions of the ring structure and of the fiber integration map. The uniqueness of differential cohomology (up to unique natural transformation) is proved by deriving an explicit formula for any natural transformation between a differential cohomology theory and the model given by differential characters. Fiber integration for fibers with boundary is treated in the context of relative differential characters. As applications we treat higher-dimensional holonomy, parallel transport, and transgression.},
  language  = {en}
}
@article{Becker2014,
  author    = {Becker, Christian},
  title     = {Relative differential cohomology},
  series = {Lecture notes in mathematics : a collection of informal reports and seminars},
  volume    = {2112},
  journal   = {Lecture notes in mathematics : a collection of informal reports and seminars},
  publisher = {Springer},
  address   = {Berlin},
  isbn      = {978-3-319-07034-6; 978-3-319-07033-9},
  issn      = {0075-8434},
  doi       = {10.1007/978-3-319-07034-6_2},
  pages     = {91 -- 180},
  year      = {2014},
  abstract  = {We study two notions of relative differential cohomology, using the model of differential characters. The two notions arise from the two options to construct relative homology, either by cycles of a quotient complex or of a mapping cone complex. We discuss the relation of the two notions of relative differential cohomology to each other. We discuss long exact sequences for both notions, thereby clarifying their relation to absolute differential cohomology. We construct the external and internal product of relative and absolute characters and show that relative differential cohomology is a right module over the absolute differential cohomology ring. Finally we construct fiber integration and transgression for relative differential characters.},
  language  = {en}
}