{
  "format": "sokoban-web-v1",
  "title": "Sokoban Optimization",
  "benchmark_id": "xsokoban-gap10-draft-2026-10-26",
  "status": "draft",
  "snapshot_date": "2026-10-26",
  "manifest_sha256": "0eefd3c45e8f071a5d1a8a5165e7abb1e39a50747a631b5c8a3f20ca7e464d89",
  "evidence_ready": false,
  "scoreable": false,
  "release_ready": false,
  "research_status": "Public-source audit complete. All ten lower bounds independently checked; record solution replays pending.",
  "selection": "ten largest documented gaps in XSokoban after excluding 73 reported optimal solves",
  "sources": [
    {
      "label": "Independently checked lower-bound certificates · 26 October 2026",
      "path": "lower-certificates.json",
      "sha256": "7aa618c928261bf2d310726c4464855e73089634e9fb997619846776c5187219"
    },
    {
      "label": "Published comparison bounds · IJCAI 2016, Table 1",
      "url": "https://ijcai.org/proceedings/2016/0100.pdf"
    },
    {
      "label": "XSokoban solution records · 28 April 2026",
      "url": "https://sokoban-solver-statistics.sourceforge.io/statistics/XSokoban/XSokoban.html"
    },
    {
      "label": "Sokolution 7.32 push-optimal test",
      "url": "https://sokoban-solver-statistics.sourceforge.io/statistics/Push-OptimalTestSuite/Sokolution%20-%20XSokoban.html"
    },
    {
      "label": "Original XSokoban 3.3c boards · Cornell",
      "url": "https://www.cs.cornell.edu/andru/release/xsokoban-3.3c.tar.gz"
    }
  ],
  "instances": [
    {
      "id": "xsokoban-50",
      "label": "XSokoban 50",
      "lower": 104,
      "upper": 370,
      "board_sha256": "d6f86a2a022aa54b1d83f17e22cfa568ad62545f924361f49ae2f27dec617e55",
      "board": "###################\n#######..    #   ##\n######..* $    $ ##\n#####..*.# # # $###\n####..*.# # # $  ##\n####...#  #    # ##\n#  ## #          ##\n# @$ $ ###  #   ###\n# $   $   # #   ###\n###$$   # # # # ###\n###   $   # # #####\n### $# #####      #\n###$   #####    # #\n###  ########     #\n###  ########    ##\n###################\n",
      "width": 19,
      "height": 16,
      "boxes": 16,
      "push_parity": 0,
      "record_url": "https://www.letslogic.com/level/58203",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 102,
      "lower_certificate": "evidence/lower/xsokoban-50-abstraction.json",
      "lower_certificate_sha256": "3d7d59d4de0641c2531782d5bc97bc60a32f3a501592c587898fa47ccaaf5c7a",
      "audit": {
        "id": "xsokoban-50",
        "declared_lower": 104,
        "declared_upper": 370,
        "push_parity": 0,
        "verified_lower": 104,
        "replayed_upper": null,
        "problems": [
          "upper-bound witness missing"
        ]
      }
    },
    {
      "id": "xsokoban-69",
      "label": "XSokoban 69",
      "lower": 223,
      "upper": 433,
      "board_sha256": "59be4374352e4b81d02fc1f376e43d2a7d7711868b4384a2db8e9509403bf48a",
      "board": "####################\n#  #      #   #   ##\n# $# $ $ ##...$  $ #\n#  $  # ##....# $  #\n# ## $ ##....#   $ #\n# $    #....## $   #\n# $##  #...#       #\n#   $$$##$##  ### ##\n# # #  #   #  #    #\n# $ #  $  ##       #\n#    #    #@       #\n####################\n",
      "width": 20,
      "height": 12,
      "boxes": 18,
      "push_parity": 1,
      "record_url": "https://www.letslogic.com/level/946",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 223,
      "lower_certificate": "evidence/lower/xsokoban-69-abstraction.json",
      "lower_certificate_sha256": "66c5a31f278c183e8a430b4ef4969d0b11e81f3012fa5b8e3b18d979e01d818c",
      "audit": {
        "id": "xsokoban-69",
        "declared_lower": 223,
        "declared_upper": 433,
        "push_parity": 1,
        "verified_lower": 223,
        "replayed_upper": null,
        "problems": [
          "upper-bound witness missing"
        ]
      }
    },
    {
      "id": "xsokoban-66",
      "label": "XSokoban 66",
      "lower": 193,
      "upper": 325,
      "board_sha256": "9fea75636321b79e19dbdd3a7733984a528a21fe6b618a191df8c385c276169b",
      "board": "####################\n#     #  #...#@    #\n# #       ....#    #\n#  $  #   #....#   #\n# ##$#### ##....#  #\n# $   $  #  #...#  #\n# $$ #   #   # $$  #\n###  $$$#   $$  $  #\n# $  #  #    # $#  #\n#   $#  #       $  #\n#  #    #    #  #  #\n####################\n",
      "width": 20,
      "height": 12,
      "boxes": 18,
      "push_parity": 1,
      "record_url": "https://www.letslogic.com/level/943",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 193,
      "lower_certificate": "evidence/lower/xsokoban-66-abstraction.json",
      "lower_certificate_sha256": "1d4324888e8dc2940618d8911d885c8013b945ffbd17ef8763f112f9667f58e5",
      "audit": {
        "id": "xsokoban-66",
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        "declared_upper": 325,
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        "replayed_upper": null,
        "problems": [
          "upper-bound witness missing"
        ]
      }
    },
    {
      "id": "xsokoban-52",
      "label": "XSokoban 52",
      "lower": 379,
      "upper": 421,
      "board_sha256": "4d1caeaba26f1f63bc10e203b4b1405c8ee808ce67483a620a63ce02574aa90b",
      "board": "###################\n############......#\n############......#\n####  #########...#\n#### $   $    #...#\n####  # # # # #   #\n##### # # #@# #   #\n#   # ### ### ## ##\n#    $ # $ $ $ # ##\n# $$$  $   #     ##\n#   # ###$###$## ##\n### #  $   #     ##\n### $  # $ $ $ ####\n##  # ### ### #####\n## $          #####\n##  ###############\n###################\n",
      "width": 19,
      "height": 17,
      "boxes": 18,
      "push_parity": 1,
      "record_url": "https://www.letslogic.com/level/929",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 379,
      "lower_certificate": "evidence/lower/xsokoban-52-abstraction.json",
      "lower_certificate_sha256": "d3720d818a613c0d82bc54a49e77d5ac3e8fa2ca47ab5b497752a9434799199f",
      "audit": {
        "id": "xsokoban-52",
        "declared_lower": 379,
        "declared_upper": 421,
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        "verified_lower": 379,
        "replayed_upper": null,
        "problems": [
          "upper-bound witness missing"
        ]
      }
    },
    {
      "id": "xsokoban-37",
      "label": "XSokoban 37",
      "lower": 246,
      "upper": 284,
      "board_sha256": "6aa346a7ac69d38c1eb721251d04e0e900c0a43ea6f746fe819a5a38712c1409",
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      "width": 19,
      "height": 15,
      "boxes": 20,
      "push_parity": 0,
      "record_url": "https://www.letslogic.com/level/58175",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 246,
      "lower_certificate": "evidence/lower/xsokoban-37-abstraction.json",
      "lower_certificate_sha256": "c589d40d2393bafc28547955333d3d6f023e9a3baa726dffb6b6712b1a059ef6",
      "audit": {
        "id": "xsokoban-37",
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        "problems": [
          "upper-bound witness missing"
        ]
      }
    },
    {
      "id": "xsokoban-74",
      "label": "XSokoban 74",
      "lower": 194,
      "upper": 212,
      "board_sha256": "0bdc91008dd99cfcd266202b8cd4ca87da7969c77459641f3abf34634f241ec6",
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      "width": 20,
      "height": 12,
      "boxes": 16,
      "push_parity": 0,
      "record_url": "https://www.letslogic.com/level/951",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 190,
      "lower_certificate": "evidence/lower/xsokoban-74-abstraction.json",
      "lower_certificate_sha256": "cf3e2b91ea7f26f89495425d58b9efb056643c2ea77c22c1360efbeef887df21",
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      }
    },
    {
      "id": "xsokoban-13",
      "label": "XSokoban 13",
      "lower": 224,
      "upper": 238,
      "board_sha256": "ae1aebb28663a8814065a8ff90205aa5973f2771e876615f841e0c5f45c0436e",
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      "width": 19,
      "height": 13,
      "boxes": 16,
      "push_parity": 0,
      "record_url": "https://www.letslogic.com/level/890",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 224,
      "lower_certificate": "evidence/lower/xsokoban-13-abstraction.json",
      "lower_certificate_sha256": "1f8b5830f83a0416b1805f344e599969f343e3feb4b972d684651a64aab0541e",
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    },
    {
      "id": "xsokoban-15",
      "label": "XSokoban 15",
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      "width": 17,
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      "record_url": "https://www.letslogic.com/level/892",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 108,
      "lower_certificate": "evidence/lower/xsokoban-15-abstraction.json",
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      }
    },
    {
      "id": "xsokoban-22",
      "label": "XSokoban 22",
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      "record_url": "https://www.letslogic.com/level/899",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 310,
      "lower_certificate": "evidence/lower/xsokoban-22-abstraction.json",
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      }
    },
    {
      "id": "xsokoban-31",
      "label": "XSokoban 31",
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      "upper": 250,
      "board_sha256": "88a26d4a3f5dbe352eaeb842e8da89fa993260aec96be7dab86827576acc2a23",
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      "width": 18,
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      "record_url": "https://www.letslogic.com/level/908",
      "lower_source": "Independently recomputed additive box-pattern certificate, 2026-10-26",
      "upper_source": "Let's Logic live Site Push Record, checked 2026-10-26; corroborates the 2026-04-28 statistics table",
      "published_lower": 236,
      "lower_certificate": "evidence/lower/xsokoban-31-abstraction.json",
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  ]
}