On a Simple Method for Detecting Synchronization
		Errors in Coded Messages

	S. Konstantinidis, S. Perron, L. A. Wilcox-O'Hearn

The concepts of unique decodability (or decipherability) and
decodability with finite delay have been studied in connection with
coded languages (sets of coded messages) and, in some cases, in the
presence of channel errors. On the other hand, the concepts of 
error-correction and -detection have been studied primarily
in connection with uniform-length (or fixed-length) codes. In
this paper, we study the method of separators for detecting
synchronization (and substitution) errors, with finite delay, in
 coded languages of the form $(pCs)^*$, where $(p,s)$ 
is a pair of words (the separators) and $C$ is a uniform-length
code. We consider the cases where the errors are scattered or
occur in bursts, and we evaluate a pair $(p,s)$ in terms
of the redundancy $|p|+|s|$, 
the delay of decoding, and the frequency of the detectable errors. 
The burst error-detecting ability of $(p,s)$ strongly
depends on the period of the word $sp$.