{
  "original": true,
  "figure": "null-frame-and-degeneracies",
  "normal_plane": {
    "metric": "G=dt²-dx_normal²",
    "c": 1,
    "r": 1,
    "coordinate_label_order": "(t,x_normal)",
    "N": [
      -1,
      1
    ],
    "L": [
      0.5,
      0.5
    ],
    "nu": [
      -0.25,
      -0.25
    ],
    "H": [
      0,
      -1
    ]
  },
  "table_columns": [
    "section/point",
    "kappa1*r²",
    "kappa2*r²",
    "K*r²",
    "R1/r²,R2/r²"
  ],
  "table_exact_rows": [
    [
      "time sphere",
      "1/4",
      "1/4",
      "1",
      "4, 4"
    ],
    [
      "equator, ε = 1/6",
      "0",
      "1/4",
      "1/2",
      "∞, 4"
    ],
    [
      "equator, ε = 1/3",
      "-1/4",
      "1/4",
      "0",
      "-4, 4"
    ],
    [
      "north, w = (1-z)/2",
      "0",
      "0",
      "0",
      "∞, ∞"
    ]
  ],
  "infinite_focal_semantics": "no finite focal parameter",
  "proof_locators": [
    "manuscript M2–M5,M7",
    "learner Theorem2, eq(13)–(17), examples, Exercise6"
  ],
  "human_source": "Riesz1949 §68 pp138–141; degeneracy extension and Gaussian identity derived here"
}