# C1454 — Explain the preserved MT–SP cumulative610 gap

## Question

Why does the MT–SP cumulative source-head gap survive both primary inverse stages?

## Sources

```json
[
  "MT and SP cumulative original and inverse legs"
]
```

## Opened utc

2026-09-29T01:16:15.058798+00:00

## Results

```json
{
  "source_legs_difference": [
    120,
    490
  ],
  "inverse_legs_difference": [
    2100,
    -1490
  ],
  "head_gaps": [
    610,
    610,
    610
  ],
  "intermediate_gaps": [
    120,
    2100
  ]
}
```

## Finding

The common−1980 contraction preserves the610 head gap, while a1980 transfer changes component differences(120,490) to(2100,−1490). It preserves heads, not the full primary path.

## Reassessment

Compare the LXX upper-leg change, where the same contraction no longer applies.

## Checks

```json
{
  "heads610": true,
  "different_interiors": true
}
```

## Closed utc

2026-09-29T01:16:15.059219+00:00

## Record provenance

Exact record hash: `b9e5ee53f94d1a10866561bcff00b79f5c6c8898c53485ada33f3b331cf0d5a6`

Source journal: `Research_Cycles/C1433_C1482/journal.json`