Suppose that for a given set of events $e_1,\ldots,e_n$, an expert
describes which event precedes which (we will denote this precedence
relation by $e_i* off-line*, i.e., they require that the
entire data is known before they can start working. In the paper under
review, an * on-line* algorithm is presented for checking
consistency. In other words, if we have an interval order, and we add
a new event $e$, with a list of events that precede $e$ and a list of
events that are preceded by $e$, then this algorithm checks whether
the resulting relation is an interval order
in time that is linear in the size of
the added data (i.e., in the size of these two lists).