  In the current paper we provide a proof of NP-completeness for the CFP
problem with the fractional grouping efficacy objective. For this purpose we
first consider the CFP with the linear objective minimizing the total number of
exceptions and voids. Following the ideas of Pinheiro et al. (2016) we show
that it is equivalent to the Bicluster Graph Editing Problem (BGEP), which is
known to be NP-complete (Amit, 2004). Then we suggest a reduction of the CFP
problem with the linear objective function to the CFP with the grouping
efficacy objective.
