# RCIG Erratum — SCNF Critical-Pair Basis v0.1 Overlap-Class Metadata

**Date:** 2026-09-13  
**Discovered in:** Run 160  
**Affected artifact:** `RCIG_SCNF_Critical_Pair_Basis_v0.1.json`

## Summary

The substantive Run 158 / Run 159 normalization result remains valid:

$$
512\text{ configurations},
\quad
1056\text{ edges},
\quad
832\text{ critical pairs},
$$

with:

$$
1056/1056
$$

strict measure descent and:

$$
832/832
$$

one-step diamonds.

However, the v0.1 statement that these critical pairs formed:

$$
9
$$

canonical overlap classes was representation-order dependent.

## Cause

v0.1 used:

```text
ancestor
descendant
```

to describe the relative paths of the two branches of an **unordered** critical pair.

Which branch was called first depended on implementation edge ordering.

An independent verifier using a different ordering therefore split the same semantic overlap patterns differently.

## Correction

Basis v0.2 uses the symmetric path relation:

```text
same
nested
disjoint
```

and obtains:

$$
\boxed{
8
}
$$

order-invariant overlap classes.

Corrected semantic fingerprint:

```text
22940d7692769c3ae8747c29d8fe7cebe326566500b837dedab6e198c74d4f33
```

Corrected Basis v0.2 payload SHA256:

```text
90fcdae6d417aef8bf8a0873395e4e8d1aefc1d18abfffba6093e59de5e8a1f7
```

## Scope of the Erratum

This erratum changes **overlap-class metadata only**.

It does not retract the verified termination or local-confluence facts.

Basis v0.2 supersedes v0.1 for theorem-summary and differential-verification purposes.