Pest Management on Deciduous Fruits: Multidisciplinary Aspects
From the time the first broad-spectrum, synthetic pesticides were developed and used on deciduous fruits in the late 1940s until the early 1960s, pest control was treated as an isolated aspect of fruit production in many areas. Extensive chemical control programs utilizing insecticides, fungicides, and acaricides were developed. Frequently, the control of one pest would aggravate problems with a second pest, so additional chemicals were used to control the second pest. Orchard sanitation and cultural practices which might have aided in pest control were largely ignored.
We continue the study of bottom-up unranked tree automata with equality and ::: disequality constraints between direct subtrees. In particular, we show that ::: the emptiness problem for the nondeterministic automata is decidable. In ::: addition, we show that the universality problem, in contrast, is undecidable.