Ключевые слова: abstract, background, blackboard, building, ceiling, circumference, clean, constant, contemporary, definition, design, education, floor, glass, glassy, greek, hall, knowledge, letter, lights, math, mathematical, mathematics, mirror, number, perspective, pi, principle, public, real, reflection, reflectzion, school, science, screen, station, structure, symbol, texture, transparent, underground, urban, wall, white,