  This volume contains the papers presented at LINEARITY 2016, the Fourth
International Workshop on Linearity, held on June 26, 2016 in Porto, Portugal.
The workshop was a one-day satellite event of FSCD 2016, the first
International Conference on Formal Structures for Computation and Deduction.
  The aim of this workshop was to bring together researchers who are developing
theory and applications of linear calculi, to foster their interaction and
provide a forum for presenting new ideas and work in progress, and enable
newcomers to learn about current activities in this area. Of interest were new
results that made a central use of linearity, ranging from foundational work to
applications in any field. This included: sub-linear logics, linear term
calculi, linear type systems, linear proof-theory, linear programming
languages, applications to concurrency, interaction-based systems, verification
of linear systems, and biological and chemical models of computation.
