Probability Basics Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-129

Effect

Computation or source lookup only

Input and validation requirements

• Division by zero occurs when P(B)=0; the calculator must reject or clearly report an undefined conditional probability or Bayes result.
• Invalid probabilities below 0 or above 1 must be rejected.
• Inconsistent event inputs can produce misleading results unless bounds such as P(A∩B)≤P(A) and P(A∩B)≤P(B) are enforced when the corresponding values are supplied.
• Expected-value tables with probabilities that do not sum to 1 require rejection or explicit normalization behavior; normalization is not specified.
• Rounding can make a probability table sum slightly above or below 1, so the accepted tolerance is unspecified.
• Infinite or very large outcome tables can make expected-value computation divergent, overflow, or lose precision.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "P_A_intersection_B": 0.18,
    "P_B": 0.3
  },
  "expected_outputs": {
    "P_A_given_B": 0.6
  },
  "working": "P(A|B)=P(A∩B)/P(B)=0.18/0.30=0.60."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json