“…Also, differential equations with operations on the space variable received great attention starting with Carleman [6] (equations with shift (involution)) and followed with great attention by Przewoerska-Rolewicz [17,18,19,20,21,22,23], Aftabizadeh et al [1], Andreev [3], [4], Burlutskayaa et al [5], Gupta [7], [8], [9], Watkins [31], Viner [29], [30], and Wiener [32], [33]; for spectral problems and inverse problems for equations with involutions we may cite the recent works of Kaliev et al [10], [11], Sadybekov et al [15], [16], [25], Sarsenbi et al [13], [26] and [27]. The papers of Aliev [2] and Rus [24] concern the maximum principle for equations with a delay in the space variable.…”