ODL (Object Definition Language) — Association Degree Support Within ODL, which degrees of association relationships are supported when modeling links between objects?

Introduction:
ODL (Object Definition Language), as used in ODMG-style object databases, describes classes, attributes, relationships, and constraints for persistent objects. A frequent modeling question is how many participating object types an association can connect (its arity or degree).

Given Data / Assumptions:

• ODL models relationships explicitly, often with role names and cardinalities.
• Associations may be unary (reflexive), binary, ternary, or higher.
• The question asks about the spectrum of support.

Concept / Approach:
Just like conceptual ER modeling, object models can define relationships of arbitrary degree. Although higher-arity relationships are less common and may sometimes be decomposed into sets of binary links with additional classes, the language and modeling approach conceptually allow arbitrary arity when it accurately represents the domain semantics.

Step-by-Step Solution:
1) Recognize that unary associations relate an object to itself (for example, manages relationship).2) Binary associations connect two object types (for example, Customer–Order).3) Ternary associations connect three object types (for example, Supplier–Part–Project).4) Higher-degree associations are also representable, though sometimes normalized via helper classes.5) Therefore, ODL supports unary, binary, ternary, and higher-degree associations.

Verification / Alternative check:
Modeling literature and ODL examples include n-ary associations; practical systems may recommend decomposition for clarity or performance, but the language and modeling concept do not forbid higher arity.

Why Other Options Are Wrong:

• Unary only / Binary only: Too restrictive; does not reflect ODL's modeling scope.
• Up to ternary only: Artificial cut-off; higher-arity is possible.

Common Pitfalls:
Forcing all real-world ternary or higher constraints into binary links and then losing the intended semantics. When decomposition is used, ensure constraints are preserved with additional classes and checks.

Final Answer:
Unary and Binary and Ternary and higher