The Separate Universe Approach to Soft Limits
  We develop a formalism for calculating soft limits of $n$-point inflationary
correlation functions using separate universe techniques. Our method naturally
allows for multiple fields and leads to an elegant diagrammatic approach. As an
application we focus on the trispectrum produced by inflation with multiple
light fields, giving explicit formulae for all possible single- and double-soft
limits. We also investigate consistency relations and present an infinite tower
of inequalities between soft correlation functions which generalise the
Suyama-Yamaguchi inequality.
