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1.Why do we need name spaces?

We need namespaces to provide a unique identifier for a set of names in the context of a particular application or domain. Namespaces are used in various technologies such as XML, RDF, and OWL to prevent naming collisions and ensure that names are globally unique. For example, consider an XML document that uses elements named "title" and "author". These names are commonly used in many different contexts, so using them without a namespace could lead to ambiguities or conflicts. By defining a namespace, such as "http://example.com/library", we can create unique names for these elements, such as "lib:title" and "lib:author". Namespaces also help to organize and categorize names based on their purpose or meaning. For example, in RDF, the Dublin Core Metadata terms are defined in the "http://purl.org/dc/elements/1.1/" namespace, and the FOAF vocabulary for describing people is defined in the "http://xmlns.com/foaf/0.1/" namespace. Using namespaces allows us to easily distinguish between different sets of names and the contexts in which they are used.