In his News Feature “Sea of doubts” (7 May, p. 560), M. Enserink reports on fraud allegations in about one-fourth the studies analyzing impact ocean acidification fish behavior. As institutions work to determine whether there is truth allegations, which have not yet been independently verified, public and policy-makers should remember that outcome will change current scientific consensus: Ocean...

We adapt an algorithm (RTI) for identifying (learning) a deterministic real-time automaton (DRTA) to the setting of positive timed strings (or time-stamped event sequences). An DRTA can be seen as a deterministic finite state automaton (DFA) with time constraints. Because DRTAs model time using numbers, they can be exponentially more compact than equivalent DFA models that model time using stat...

A clear andpowerfulformalism for describing languages, both natural and artificial, follows f iom a method for expressing grammars in logic due to Colmerauer and Kowalski. This formalism, which is a natural extension o f context-free grammars, we call "definite clause grammars" (DCGs). A DCG provides not only a description of a language, but also an effective means for analysing strings o f tha...