Source: https://guthlabs.ai/docs/instruments/punnett-based-trihybrid-multi-gene-probability-calculator/mechanism/

instrument mechanism / verified-with-binding-errata

# Punnett-based Trihybrid/Multi-gene Probability Calculator mechanism

The inspectable method record for Punnett-based Trihybrid/Multi-gene Probability Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **verified-with-binding-errata**

## Model scope

The core product rule is standard under independent assortment for simultaneous per-locus events. The instrument cannot receive an unconditional PASS until it explicitly defines genotype versus phenotype inputs, decimal-versus-percent representation, validation of locus count, and the precise independence assumption. The educational and not-medical-advice labeling is appropriate, but it does not resolve those computational ambiguities.

- The product rule is correct only when the per-locus events are independent and the requested outcome is the simultaneous occurrence of one specified event at every locus.

- The specification alternates between genotype probability and phenotype probability. A phenotype probability can require summing multiple genotype probabilities before applying the product rule; the current formula does not define that case.

- The role of 'number of loci' is underspecified: it must equal the number of supplied per-locus probabilities, or the calculator must reject the input.

- The formula does not state whether probabilities are supplied as decimals from 0 to 1 or as percentages from 0 to 100.

## Units and conventions

- Probabilities are dimensionless decimal fractions in the inclusive range 0 to 1; for example, 25% must be entered as 0.25.

- The number of loci is an integer of at least 3 and must equal the length of the per-locus probability list.

- Each per-locus probability refers to one specified genotype or one already-combined phenotype event.

- The loci assort independently; no linkage, epistasis, conditional dependence, or other dependence is included.

- The combined result is a decimal probability; multiply by 100 only when displaying it as a percentage.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "number_of_loci": 3,
    "per_locus_probabilities": [
      0.25,
      0.5,
      0.25
    ]
  },
  "expected_outputs": {
    "combined_probability": 0.03125,
    "combined_probability_percent": 3.125
  },
  "working": "P = 0.25 × 0.50 × 0.25\n0.25 × 0.50 = 0.125\n0.125 × 0.25 = 0.03125\n0.03125 × 100 = 3.125%"
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The plain product rule has no division-by-zero trap and no genuine multi-regime formula branch, but an implementation without strict validation can return Infinity for extreme inputs and can accept values outside the probability domain. Percentage-versus-fraction ambiguity can also produce invalid results if units are not explicit.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/punnett-based-trihybrid-multi-gene-probability-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/punnett-based-trihybrid-multi-gene-probability-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/punnett-based-trihybrid-multi-gene-probability-calculator/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`