{
 "schema_version": "0.1",
 "name": "[[50,19,3]]",
 "code_type": "CSS",
 "n": 50,
 "k": 19,
 "checks": {
  "X": [
   [
    1,
    4,
    6,
    19,
    31,
    43,
    48,
    49
   ],
   [
    2,
    3,
    11,
    18,
    31,
    36,
    45,
    48
   ],
   [
    3,
    5,
    10,
    18,
    37,
    43,
    44,
    49
   ],
   [
    2,
    4,
    11,
    19,
    25,
    35,
    37,
    44
   ],
   [
    6,
    17,
    19,
    22,
    33,
    34,
    38,
    42
   ],
   [
    1,
    5,
    7,
    9,
    27,
    30,
    39,
    41
   ],
   [
    0,
    8,
    14,
    24,
    28,
    29,
    37,
    49
   ],
   [
    1,
    4,
    9,
    15,
    26,
    28,
    33,
    42
   ],
   [
    6,
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    46
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   [
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   [
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    20,
    21,
    32,
    35,
    40,
    44
   ],
   [
    3,
    5,
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    28,
    29,
    33,
    47
   ],
   [
    2,
    4,
    15,
    21,
    29,
    30,
    39,
    47
   ],
   [
    8,
    16,
    20,
    24,
    26,
    27,
    45,
    48
   ],
   [
    12,
    17,
    22,
    23,
    26,
    28,
    48,
    49
   ]
  ],
  "Z": [
   [
    4,
    5,
    14,
    22,
    25,
    33,
    39,
    49
   ],
   [
    9,
    16,
    17,
    21,
    26,
    30,
    32,
    34
   ],
   [
    8,
    9,
    13,
    17,
    27,
    28,
    38,
    46
   ],
   [
    8,
    13,
    15,
    22,
    26,
    29,
    34,
    40
   ],
   [
    7,
    14,
    15,
    22,
    28,
    30,
    32,
    38
   ],
   [
    1,
    2,
    20,
    23,
    26,
    30,
    31,
    35
   ],
   [
    0,
    10,
    12,
    19,
    25,
    32,
    38,
    49
   ],
   [
    6,
    9,
    13,
    18,
    33,
    36,
    41,
    43
   ],
   [
    6,
    11,
    20,
    23,
    25,
    32,
    34,
    48
   ],
   [
    0,
    4,
    5,
    12,
    28,
    30,
    35,
    43
   ],
   [
    0,
    2,
    5,
    20,
    27,
    29,
    36,
    44
   ],
   [
    3,
    4,
    8,
    22,
    37,
    42,
    47,
    48
   ],
   [
    6,
    18,
    23,
    24,
    38,
    45,
    46,
    49
   ],
   [
    12,
    18,
    19,
    24,
    34,
    37,
    40,
    48
   ],
   [
    7,
    10,
    11,
    21,
    36,
    41,
    44,
    47
   ],
   [
    6,
    9,
    11,
    21,
    31,
    35,
    39,
    42
   ]
  ]
 },
 "distance": {
  "d": 3,
  "X": {
   "value": 4,
   "confidence": "upper_bound",
   "witness": [
    0,
    10,
    36,
    43
   ]
  },
  "Z": {
   "value": 3,
   "confidence": "upper_bound",
   "witness": [
    22,
    23,
    38
   ]
  }
 },
 "provenance": {
  "authors": [
   "@vprusso"
  ],
  "model": "Claude Opus 5",
  "novelty": "known_parameters",
  "origin": "submission",
  "date": "2026-09-21",
  "construction": "Check deletion from the board entry [[50,18,4]] (codes/50-18-4.json): row 0 of H_X removed. Dropping one stabiliser generator frees one logical qubit and cannot raise the distance.",
  "notes": "Found by sweeping every single-row deletion of every small board entry and keeping those that land undominated. The parent's remaining checks are unchanged."
 },
 "family": "check-deletion"
}