fourlayer

Fourlayer is a term used to describe any model, framework, or structure partitioned into four layers. It does not denote a single universal standard, but rather several independent uses across disciplines.

In software engineering, four-layer architecture divides responsibilities into presentation, application (or orchestration), domain or business logic, and data access or persistence layers. This arrangement supports separation of concerns, easier maintenance, and clearer testing strategies.

In neural networks, a four-layer network includes an input layer, two hidden layers, and an output layer. Such configurations are common in feedforward networks and can be trained with standard backpropagation; layer sizes and activation functions vary by task.

In networking, some discussions of four-layer models describe a four-layer stack mapping to link, internet, transport, and application, a simplification of the traditional seven-layer OSI model. This approach emphasizes protocol interactions at a manageable abstraction level.

In hardware or materials contexts, four-layer may describe a laminated structure, a four-layer printed circuit board with four copper layers, or four-layer composites. The exact interpretation depends on the domain.