In XML Schema design, to eliminate duplication of element definitions across multiple complex types, XML Schemas define which of the following reusable constructs?

Introduction / Context:
This question focuses on XML Schema concepts, particularly how schemas avoid repetition of element definitions. XML Schema allows designers to define global elements that can be reused in multiple complex types, leading to more maintainable and consistent schema definitions.

Given Data / Assumptions:

- The question mentions eliminating definition duplication.- The context is XML Schema, not relational databases.- Several options refer to different constructs, some of which belong to relational models rather than XML.

Concept / Approach:
In XML Schema, global elements are declared at the schema level and can be referenced by multiple complex types. This avoids redefining the same element structure in several places and promotes reuse. This approach is analogous to defining a reusable type or class in programming. Intersection tables and normalization are relational database concepts, not XML Schema mechanisms. Understanding these distinctions helps identify the correct construct.

Step-by-Step Solution:
Step 1: Recognize that the context is XML Schema, which uses elements and types to describe XML document structure.Step 2: Recall that global elements are defined at the top level of a schema and can be reused by reference.Step 3: Understand that this reuse mechanism directly addresses duplication of element definitions.Step 4: Note that intersection tables and normalized tables belong to relational database design, not to XML Schema.Step 5: Schema views and separate document type declarations are not the standard XML Schema terminology for reusable element definitions.Step 6: Conclude that global elements are the correct reusable construct used to eliminate definition duplication.

Verification / Alternative check:
Documentation for XML Schema describes global elements and complex types as top level components that can be referenced by name in multiple places. For example, a global element representing an address can be used in both billing and shipping sections without redefining its structure. This reuse is exactly how schemas avoid duplication, confirming the role of global elements.

Why Other Options Are Wrong:
Option A, intersection table, is a relational database concept used to resolve many to many relationships and does not apply to XML Schema. Option C, normalized definition table, again belongs to relational normalization. Option D, schema views, is not a standard XML Schema construct for reusable elements. Option E suggests separate document type declarations, which relates to DTDs rather than the specific reuse mechanism described.

Common Pitfalls:
A frequent mistake is to mix relational database terminology with XML Schema terminology, assuming that similar ideas must have identical names across technologies. Remember that XML Schema has its own constructs such as global elements and types, and that these are distinct from tables, keys, and intersection tables used in relational models.

Final Answer:
XML Schemas eliminate duplication of element definitions by using global elements that can be reused across complex types.