  This paper investigates how often the popular configurations of Differential
Evolution generate solutions outside the feasible domain. Following previous
publications in the field, we argue that what the algorithm does with such
solutions and how often this has to happen is important for the overall
performance of the algorithm and interpretation of results. Based on
observations therein, we conclude that significantly more solutions than what
is usually assumed by practitioners need to undergo some sort of 'correction'
to conform with the definition of the problem's search domain. A wide range of
popular Differential Evolution configurations is considered in this study.
Conclusions are made regarding the effect the Differential Evolution components
and parameter settings have on the distribution of proportions of infeasible
solutions generated in a series of independent runs. Results shown in this
study suggest strong dependencies between proportions of generated infeasible
solutions and every aspect mentioned above. Further investigation of the
distribution of proportions of generated infeasible solutions is required.
