This paper presents a new efficient algorithm for mining frequent closed itemsets. It enumerates the closed set of frequent itemsets by using a novel compound frequent itemset tree that facilitates fast growth and eff...This paper presents a new efficient algorithm for mining frequent closed itemsets. It enumerates the closed set of frequent itemsets by using a novel compound frequent itemset tree that facilitates fast growth and efficient pruning of search space. It also employs a hybrid approach that adapts search strategies, representations of projected transaction subsets, and projecting methods to the characteristics of the dataset. Efficient local pruning, global subsumption checking, and fast hashing methods are detailed in this paper. The principle that balances the overheads of search space growth and pruning is also discussed. Extensive experimental evaluations on real world and artificial datasets showed that our algorithm outperforms CHARM by a factor of five and is one to three orders of magnitude more efficient than CLOSET and MAFIA.展开更多
The paper examined the state of GIS （geographic information systems） knowledge and adoption in Nigeria, identified factors affecting its implementation and finally discussed methods of enhancing its use in Nigeria. ...The paper examined the state of GIS （geographic information systems） knowledge and adoption in Nigeria, identified factors affecting its implementation and finally discussed methods of enhancing its use in Nigeria. Administrative records of some institutions and information obtained from published articles in journals and text books were used for the study. Records indicate that GIS is relatively young in Nigeria and in terms of development, it is at its youthful stage. The adoption and use of GIS is low at both Federal and State Government levels. However, factors such as, lack of political will, shortage of experts to train the professionals, lack of standardization of digital data, database development and management problems, institutional constraints, security implications of digital maps and poor funding have been inhibiting full adoption, implementation and use of GIS in Nigeria. There is the need to develop a GIS vision in the country and government should formulate policy and create enabling environment for the adoption and implementation of the new technology.展开更多
文摘This paper presents a new efficient algorithm for mining frequent closed itemsets. It enumerates the closed set of frequent itemsets by using a novel compound frequent itemset tree that facilitates fast growth and efficient pruning of search space. It also employs a hybrid approach that adapts search strategies, representations of projected transaction subsets, and projecting methods to the characteristics of the dataset. Efficient local pruning, global subsumption checking, and fast hashing methods are detailed in this paper. The principle that balances the overheads of search space growth and pruning is also discussed. Extensive experimental evaluations on real world and artificial datasets showed that our algorithm outperforms CHARM by a factor of five and is one to three orders of magnitude more efficient than CLOSET and MAFIA.
文摘The paper examined the state of GIS （geographic information systems） knowledge and adoption in Nigeria, identified factors affecting its implementation and finally discussed methods of enhancing its use in Nigeria. Administrative records of some institutions and information obtained from published articles in journals and text books were used for the study. Records indicate that GIS is relatively young in Nigeria and in terms of development, it is at its youthful stage. The adoption and use of GIS is low at both Federal and State Government levels. However, factors such as, lack of political will, shortage of experts to train the professionals, lack of standardization of digital data, database development and management problems, institutional constraints, security implications of digital maps and poor funding have been inhibiting full adoption, implementation and use of GIS in Nigeria. There is the need to develop a GIS vision in the country and government should formulate policy and create enabling environment for the adoption and implementation of the new technology.
