| The ever increasing of database related to time makes designing temporal database very important. In the design of temporal database, it is necessary to give full consideration to the data dependent treatment. Data dependency means all kinds of connections among data. The happening of data redundance is connected with data dependency. Data dependency is a central notion in database design theory through which we can normalize intrinsic semantic restrinction among attributes.In order to make the study, the relation of all the dependences and all the attributes, more efficient, then normalize relational database one more step, in this paper, the notions of temporal left attributes, temporal right attributes, temporal both-rl attributes, temporal functional dependency graph are introduced. And the algorithms for temporal candidate keyword sets is given use graph theory method and absorption method respectively, its correction are given.Temporal functional dependency (TFD) and temporal multi-valued dependency (TMVD) are the two most important data-dependent in temporal database. For temporal scheme with temporal functional dependencies and temporal multi-valued dependencies constrains, the usages of multiple time granularities make it more difficult to solve membership problem. However, the solution of membership problem is essential to design an available algorithm of scheme decomposition. On the base of the strong totally orderd temporal scheme and totally orderd temporal functional dependency and the theory of regular temporal multi-valued dependency (RTMVD) of relational database, in this paper, the concepts of mix dependency base on given temporal type, mix dependency base in strong totally orderd scheme, TFD and RTMVD mix close set of strong totally orderd scheme are given. And the algorithms of dependency base of attribution sets, closure of attribution sets are given, then the proof for its termination, correction and time complexity are given. On this base, the algorithm of membership problem of mix set in strong totally orderd is given, and the proof for its termination, correction and time complexity are given.As well as, concepts of redundant dependency, mixed non-redundant cover and canonical mixed dependency set of strong-totally order temporal scheme are given. Corresponding algorithms, non-redundant cover and canonical cover, are proposed which can solve the cover problem of mixed dependency set in strong-totally orderd temporal scheme.The above research of theory and algorithm is a good solution to the problem of dependency judgement in a strong-totally mix-set of dependency, as well as, it provide theory basement for resolving the problem of normalization which in strong-totally ordered temporal scheme and the design of temporal database. |
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