Differential diagnosis
by formal evaluation

A patient describes symptoms. FR-OS evaluates 30,981 diagnoses against formally proven rules and returns a ranked differential with exclusion certificates showing why each diagnosis was ruled in or out. Every determination is auditable.

FR-OS DDx Engine

A patient describes crushing chest pain, sweating, and nausea. FR-OS identifies the clinical findings, evaluates all candidate diagnoses, and returns a ranked differential. No physician input required.

Verified medical knowledge

30,981
Diagnoses

Each with formally verified evaluation rules derived from medical knowledge bases.

855
Clinical vignettes

Validated against real clinical scenarios. The correct diagnosis appears in the differential.

100%
Engine precision

The engine is logically precise by construction. Every exclusion is a proof, not a statistical estimate.

Exclusion certificates, not probability scores

AI-based diagnosis

Neural models produce ranked lists with probability scores. "Myocardial infarction: 73% likely." There is no explanation of why, no record of what was considered, and no guarantee the model won't produce a different answer tomorrow.

FR-OS diagnosis

The engine evaluates each diagnosis against the patient's findings using formally verified rules. Diagnoses are ranked by how much evidence supports them. Each exclusion comes with a certificate showing exactly which findings ruled it out. Deterministic, auditable, reproducible.

Words matter in clinical text

Medical language is full of ambiguity. "Cold" can mean temperature or illness. "Discharge" can mean release from hospital or bodily fluid. "Positive" can mean good news or a concerning test result.

FR-OS resolves these ambiguities before clinical reasoning begins. The same engine that achieves 88.4% on standard NLP benchmarks processes clinical text, ensuring that downstream diagnosis operates on meanings, not words. This eliminates an entire class of errors where ambiguous terms match the wrong diagnoses.

Get on the waitlist

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