Publicationes Mathematicae Debrecen, cilt.82, sa.1, ss.43-58, 2013 (SCI-Expanded)
The goal of this paper includes the four-dimensional matrix charac-terization of double sequence of functions. However the main goal is to present answer to the following question. Is it necessarily the case that if sm;n(x) is a bounded for all (m; n) and x with continuous elements and P-converges to a continuous function there exists an RH-regular matrix transformation that maps (sm;n(x)) into a uniformly P-convergent double sequence?