Introduction
Lemma
Open-source language for business rules.
Total certainty
in the age of AI
Where humans, systems, and agents work together on rules.
The problem
Decision logic is hidden
Pricing, eligibility, and compliance controls are buried in code and vendor platforms. Change is slow. Audits require reconstruction.
- Business teams lose direct control over how rules are applied.
- Every adjustment becomes a technical project across multiple systems.
- Compliance teams struggle to trace, explain, and prove decisions.
What is Lemma
Rules anyone can read and write
Lemma is an open format so policy owners write rules themselves, instead of handing them to engineers to code.
Those rules become the source of truth that people, systems, and AI agents can trust.
Why Lemma
Built for governance
- Systems and AI agents never guess, and every answer can be explained.
- Reproduce any decision with the rules that applied at the given time.
- Teams can share rules and extend them.
Language
Deterministic and time-aware
Declarative logic separate from infrastructure. Readable by auditors. Bound to time. Mathematically exact.
spec pricing 2026-01-01
"""
Applies a tiered discount and VAT to the base price,
effective from 2026-01-01.
"""
data base_price: 100
data is_member: false
data quantity: number
rule discount: 0%
unless quantity >= 10 then 10%
unless quantity >= 50 then 15%
unless is_member then 20%
rule discount_amount: base_price * discount
rule discounted_price: base_price - discount_amount
rule vat: discounted_price * 21%
rule total: discounted_price + vatOpen stack
Lemma + LemmaBase
Lemma is the language. LemmaBase is where teams write, review, version, publish, and run rules in production.
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