The decision rule

An agent with value V at stake accepts claim c when

min( δ_c · CoC_low(c),  CoC(adjudicator_c) )  ≥  κ · V

• κ ≥ 1 is the consumer’s safety factor (2 in the standard policy).
• δ ≤ 1 is the claim’s detection factor (detection_permille / 1000): how reliably a falsehood of this kind is proven.
• CoC(adjudicator) caps trust at the cost of corrupting the dispute process. A claim with no adjudicator has no cap (∞). It also cannot be challenged at all in this implementation, because automatic slashing on cryptographic evidence is not built.

The network proves the formula and the bonds behind it; each consumer evaluates its own policy locally, in time linear in the formula’s size.

Acceptance also needs backing

When the consumer intends to rely on the claim, acceptance also requires that at least κ · V of the claim’s backing is still unreserved, and accepting reserves it (see Reservations). The node’s decision query (sion claim decide, POST /v1/claims/{id}/decide, the MCP tool sion_assess_claim) checks both conditions; the Accept transaction checks both and then reserves.

The answer explains itself

A decision returns every intermediate value. This real answer from the devnet is for a claim resting on a 50 USD bond, with an adjudicator bonded at 200 USD, after another consumer had reserved 20 USD of its backing:

$ sion claim decide b677314a931e86fee2403fe437822ec7d087f0df37dbd9452735b16177c41634 10
{
  "accept": true,
  "adjudicator_cap": {
    "Finite": 200000000
  },
  "coc": {
    "exact": true,
    "high": {
      "Finite": 50000000
    },
    "low": {
      "Finite": 50000000
    }
  },
  "detection_adjusted": {
    "Finite": 50000000
  },
  "effective": {
    "Finite": 50000000
  },
  "reasons": [
    "cost of corruption 50 covers κ·V = 20"
  ],
  "required": 20000000,
  "reservable": {
    "Finite": 30000000
  }
}

Amounts in JSON are micro-units (1 USD = 1,000,000); the reasons use whole units.

Asking for 30 USD on the same claim fails twice over:

  "reasons": [
    "cost of corruption 50 (after detection discount 1000/1000) is below κ·V = 60",
    "only 50 of backing is unreserved; κ·V = 60 is needed"
  ],

A falsified claim is refused first of all because it is not active:

  "reasons": [
    "claim is not active (Falsified { at: Pulse(56), causes: [AtomId(05ab20b3)] })",
    "cost of corruption 0 (after detection discount 1000/1000) is below κ·V = 20",
    "only 0 of backing is unreserved; κ·V = 20 is needed"
  ],

Choosing a policy

• sion claim decide uses the standard policy, with --kappa and --distrust <atom,…>. Distrusting matters only for atoms the policy would otherwise trust. Distrusting a bond atom changes nothing, because a bond is never trusted, only counted.
• POST /v1/claims/{id}/decide takes a full policy as JSON. With an empty policy (no trusted classes), a claim resting only on a dual signature is worth 0; with the standard policy it is worth ∞:

$ curl -s -X POST http://127.0.0.1:8730/v1/claims/d47fe15d7cb445ece35b1d68c71f09afa05caace860068863642fa4aebecd23e/decide \
    -d '{"value": 10000000, "policy": {"trusted_atoms": [], "trusted_classes": [], "distrusted_atoms": [], "assumed_broken": [], "kappa": {"num": 2, "den": 1}}}'
{"accept":false,"adjudicator_cap":"Infinite","coc":{"exact":true,"high":{"Finite":0},"low":{"Finite":0}},"detection_adjusted":{"Finite":0},"effective":{"Finite":0},"reasons":["cost of corruption 0 (after detection discount 1000/1000) is below κ·V = 20","only 0 of backing is unreserved; κ·V = 20 is needed"],"required":20000000,"reservable":{"Finite":0}}

Agent Charters use it too

A charter can require evidence above a threshold: a payment larger than evidence_above must cite a claim that passes the decision rule under the principal’s evidence_policy, for the payment’s amount. See Agent Charters.