# C796 — Explain the BJ fifty-year contraction by its two components

## Question

Why does removing57 appear as2450→2400?

## Inputs

```json
{}
```

## Sources

```json
[
  "File53 §3A; literal trunk roles"
]
```

## Opened utc

2026-09-28T02:06:05.299719+00:00

## Results

```json
{
  "spans": {
    "Creation_to_Conquest": 2450,
    "Fall_to_rest": 2450,
    "compressed_Creation_to_rest": 2400,
    "compressed_Fall_to_rest_diagnostic": 2393,
    "compressed_Creation_to_Conquest_diagnostic": 2393
  },
  "net_change": 50
}
```

## Finding

The displayed reduction50 combines a57 deletion with a7-year change of starting role. Deleting57 from the Fall while retaining rest yields2393, so the2450→2400 relation requires its declared endpoint pairing.

## Reassessment

Test the positive four-node reflection in its actual comparison domain.

## Checks

```json
{
  "paired2450": true,
  "compressed2400": true,
  "controls2393": true
}
```

## Closed utc

2026-09-28T02:06:05.300356+00:00

## Record provenance

Exact record hash: `8a43474523aad383d2992ccc8914d6af67746bc2728ff6821508190129210ecd`

Source journal: `Research_Cycles/C0732_C0831/journal.json`