Hamming Distance / Error-Detection 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

t4-266

Effect

Computation or source lookup only

Input and validation requirements

• Unequal-length inputs must be rejected before comparison; silently truncating, padding, or comparing only the overlapping prefix would produce an invalid result.
• The detection and correction capabilities are not validly determined from an arbitrary pairwise distance unless that distance is known to be the code's minimum distance.
• For d=0, the raw formulas produce −1 for both capabilities, which is not a meaningful error-detection or correction guarantee; capability outputs need a validity constraint such as d≥1 and a defined code minimum distance.
• Text handling is ambiguous for Unicode strings: code units, code points, and user-perceived characters can yield different lengths and distances.
• Empty strings produce distance 0 and require explicit handling.
• No division-by-zero hazard exists in the stated formulas.

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": {
    "x": "0000",
    "y": "0001"
  },
  "expected_outputs": {
    "hamming_distance": 1,
    "differing_positions": [
      4
    ],
    "detects_up_to_errors": 0,
    "corrects_up_to_errors": 0
  },
  "working": "Compare positions: 1: 0=0, no difference; 2: 0=0, no difference; 3: 0=0, no difference; 4: 0≠1, one difference. Therefore d=0+0+0+1=1. Detection: d−1=1−1=0. Correction: floor((d−1)/2)=floor(0/2)=0."
}

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