{"id": "c1215", "title": "C1215 — Explain the exact cancellation in the Rounded head difference", "filename": "C1215.md", "role": "Research action", "step": 1215, "sha256": "b932233dca6966a9dd61f15f26370d924e73453648b491e7bd3775c25ed96a10", "bytes": 1315, "origins": ["C480–C1634/Research_Cycles/C1132_C1431_Recovered/journal.json#C1215"], "download": "/sources/b932233dca6966a9dd61f15f26370d924e73453648b491e7bd3775c25ed96a10.md", "format": "md", "derived": true, "tags": ["Cumulative", "Rounded"], "excerpt": "Why do local rounding changes preserve the total430?", "content": "# C1215 — Explain the exact cancellation in the Rounded head difference\n\n## Question\n\nWhy do local rounding changes preserve the total430?\n\n## Inputs\n\n```json\n{}\n```\n\n## Sources\n\n```json\n[\n  \"C1214\"\n]\n```\n\n## Opened utc\n\n2026-09-28T05:29:10.374185+00:00\n\n## Results\n\n```json\n{\n  \"cancellation\": {\n    \"path\": \"model/whole_genealogy_rounded_head_cancellation.json\",\n    \"sha256\": \"3d45a7d600eda8d3b759b2b612bd9ca5267b4804fb9b58fa83e23698e46fce33\",\n    \"bytes\": 436\n  },\n  \"located_errors\": [\n    {\n      \"name\": \"Lamech\",\n      \"difference_error\": 4\n    },\n    {\n      \"name\": \"Arphaxad\",\n      \"difference_error\": -2\n    },\n    {\n      \"name\": \"Shelah\",\n      \"difference_error\": -2\n    }\n  ]\n}\n```\n\n## Finding\n\nThe Rounded Cumulative total remains430 because Lamech contributes+4 and Arphaxad/Shelah contribute−2 each. The cancellation explains the shared head while predicting an internal displacement field.\n\n## Reassessment\n\nReconstruct the internal rounding-displacement field rather than stop at its zero total.\n\n## Checks\n\n```json\n{\n  \"cancels\": true,\n  \"heads430\": true\n}\n```\n\n## Closed utc\n\n2026-09-28T05:29:10.374656+00:00\n\n## Record provenance\n\nExact record hash: `268065dc94c7df85f65656030e021aa590c9aa49622bcf48c4a9fb9d73239916`\n\nSource journal: `Research_Cycles/C1132_C1431_Recovered/journal.json`", "journalDownload": "/sources/6adb632ce171623c2bce60d7ed58ae319ccb379cf76b751c0a477c1742fd348c.json", "evidenceLinks": [{"id": "d-3d45a7d600eda8d3", "title": "model/whole_genealogy_rounded_head_cancellation.json"}]}