الفهرس 
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Abstract
Current generation data models lack direct support for relationships,data abstraction inheritance constraints explict representation of objects and the dynamic properties of an pllication semantic data models have emerged from a requirement for more expressive conceptual data models.Although many researches have focused on developing new semantic models little work has been directed at providing methodological support for selecting an appropriate semantic model or for integrating the various modeling capabilities found in semantic models.This may be attributed to the fact that most proposed semantic models are described using different languages and different(sometimes unspecified)semantics.This clarifies the need for a unified formal representation of semantic data models that inifies and generalizes their fundamental features.