Retrieval is described as the system's most differentiated subsystem because Pyrana does not treat every question as a similarity search over text and instead combines multiple retrieval strategies with semantic retrieval.

Retrieval is the system's most differentiated subsystem.

— Beyond Retrieval - Pyrana Context Engine Whitepaper.pdf

Rather than treating every question as a similarity search over text,

— Beyond Retrieval - Pyrana Context Engine Whitepaper.pdf

Pyrana selects among three complementary retrieval strategies

— Beyond Retrieval - Pyrana Context Engine Whitepaper.pdf

and then fuses their outputs with semantic retrieval.

— Beyond Retrieval - Pyrana Context Engine Whitepaper.pdf