sentences:  His initial work was in coding theory, where he (independently and simultaneously) contributed the Berlekamp-Preparata codes (optimal convolution codes for burst-error correction) and the Preparata codes, the first known systematic class of nonlinear binary codes, with higher information content than corresponding linear BCH codes of the same length.Thirty years later these codes have been found relevant to quantum coding theory.In 1967, he substantially contributed to a model of system-level fault diagnosis, known today as the PMC (Preparata-Metze-Chien) model, which is a main issue in the design of highly dependable processing systems.