Measurement of city tree cover can aid in urban vegetation planning, management, and research Blazer Nike by revealing characteristics of vegetation across a city. Urban tree cover in the United States ranges from 0.4% in Lancaster, California, to 55% in Baton Rouge, Louisiana. Two important factors that affect the amount of urban tree cover are the natural environment and land use. Urban tree cover is highest in cities that developed in naturally forested areas (31%), followed by grassland cities (19%) and desert cities (10%), but showed wide variation based on individual city characteristics. Tree cover ranged from 15 to 55% for cities in forested areas, 5 to 39% for Basket Nike Blazer Femme those in grassland areas, and 0.4 to 26% for cities developed in desert regions. Park and Acheter Blazer Nike residential lands along with vacant lands in forested areas generally have the highest tree cover among different land uses. Methods of measuring urban tree cover are presented as are planning and management implications of tree-cover data.
We consider the verification problem of programs containing the following complex features: (1) dynamic creation of parallel threads, (2) synchronisation between parallel threads via global variables, (3) (possibly recursive) procedure calls, and (4) integer variables. The configurations of such programs are represented by terms, and their transitions by term rewriting systems. The novelty of our modeling w.r.t. other existing works consists in explicitely modeling integer variables in the terms. We propose a semi-decision procedure that, in case of termination, checks whether an infinite set of configurations, represented by a regular tree language, is reachable from an infinite set of initial configurations of the program (usually represented by a set of non ground terms). As fas as we know, this is the first time that reachability between non-ground terms and regular tree languages is considered. We implemented our techniques in a tool, and tested it successfully on several examples.
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