A posteriori error estimates for fully discrete fractional-step ϑ-approximations for parabolic equations

This is a pre-copyedited, author-produced PDF of an article accepted for publication in IMA Journal of Numerical Analysis following peer review. The version of record A posteriori error estimates for fully discrete fractional-step ϑ-approximations for parabolic equations is available online at:http://imajna.oxfordjournals.org/content/early/2015/07/20/imanum.drv035.abstract?sid=ab7d6b71-cb35-42ed-896f-f009b1fdc99eWe derive optimal order a posteriori error estimates for fully discrete approximations of initial and boundary value problems for linear parabolic equations. For the discretisation in time we apply the fractional-step #-scheme and for the discretisation in space the finite element method with finite element spaces that are allowed to change with time