Topological notation in modeling and Model-Driven Engineering (MDE) is a way of representing the structural relationships within a system, network, or model without requiring exact geometric or metric details, such as distances, angles, or specific physical layouts. Instead, topological notation emphasizes the connectivity, dependencies, and relationships between elements, highlighting properties like adjacency and structural organization.

In MDE, topological notation is often applied to represent complex systems or models, where the primary focus is on logical relationships rather than spatial configuration. Examples of topological notation in MDE include:

1. Dependency and Component Diagrams: Topological notation describes modules, classes, or system components based on dependencies and interaction relationships without showing exact positioning.
2. Graph-Based Models: In network and data flow modeling, topological notation represents nodes (such as components, objects, or data points) and edges (connections or relationships) between them, focusing on connectivity rather than physical placement.
3. System Architecture Modeling: Topological views in architectural modeling represent hierarchical structures and relationships between elements, such as class inheritance or module dependencies, where structural integrity and connectivity are prioritized over specific layouts.

Topological notation is valuable in MDE because it abstracts unnecessary geometric details, allowing modelers to concentrate on essential logical structures, dependencies, and relationships that drive system functionality and design coherence. This approach is ideal for analyzing and evolving system architectures, understanding data flows, and managing component dependencies across different levels of abstraction.