We show that query plans produced by most optimizers for computing many-way joins can be easily modified to produce the query result in the form of a directionally reduced acyclic database instead of a materialized relation. Benefits of this query-plan enhancement include improved bounds on intermediate results and reductions in the cost of query evaluation.

Healthy eating is an important issue affecting a large part of the world population, so human diets are becoming increasingly popular, especially with devastating consequences Coronavirus Disease (Covid-19). A realistic and sustainable diet plan can help us to have healthy habit since it considers most expectations from without any restriction. In this study, classical problem has been extended...

the desire and drive for excellence in any endeavor in life requires an effort from the individual; in addition it requires a constellation of features around such individuals that help them to become successful. for surgeons, it is the operating room staff, the administrative and medical assistants and our residents and fellows. however, perhaps the most important contribution to a physician’s...

the first implementation of rural guide and improvement plans of iran goes back to about 20 years ago. at this period of time, at least 20 thousands plans of this type have been studied and many of them have been implemented. but in spite of spending a lot of charges by government, and bearing many problems by peasants, there is a low satisfaction of these plans, and in fact there is no signal ...

The notion of partial plans has existed ever since the early days of planning research. However, plans can be partial in many different ways, and for many different reasons. This paper presents a characterization of partial plans and discusses the use of partial plans in incremental planning under computational and informational constraints. A heuristic for guiding the generation of plausible p...

The Economy of Iran faces many challenges and is predicted to have a negative growth of 1.3 percent, unemployment of above 13 percent, and a wild inflation rate of 27.2 percent in 2013. Various external conditions and bad economic planning have contributed to Iran’s current economic difficulties. To transform the Economy of Iran, the 5th Five-year Development Plan (FYDP) and the 20-year vi...

the centralization of human activities is associated with different pollutants which enter into environment easily and cause the urban environment more vulnerable. regarding the importance of air pollution issue for tehran metropolis, many plans and regulations have been developed. however, most of them failed to decline the pollution. the purpose of this study was to pathologically analyze air...