{
  "task_id": "F5-conf-03",
  "statement_true": false,
  "counterexample_provided": true,
  "counterexample_values": {
    "construction": "X ~ N(0,1); W independent of X with P(W=1)=P(W=-1)=1/2; Y = W*X. Then Y ~ N(0,1), and X+Y = (1+W)X is 0 with probability 1/2 and 2X otherwise (atom of mass 1/2 at 0, non-constant), hence not normal.",
    "n": 100000,
    "seed": 20261029,
    "mean_x": -0.0033187423835634258,
    "sd_x": 0.9982238690893596,
    "mean_y": -0.00024909222432809854,
    "sd_y": 0.9982293548745821,
    "mean_sum": -0.0035678346078915233,
    "sd_sum": 1.4058866469982523,
    "ks_sum_vs_normal": 0.2508475723268392
  },
  "statement_b_true": true,
  "feasibility": "complete",
  "feasibility_reason": null,
  "data_issues": [],
  "n_input_rows": {
    "propositions.csv": 2,
    "design.csv": 2
  },
  "n_analysed": 100000,
  "random_seed": 20261029,
  "supplementary": {
    "ks_x_vs_normal": 0.0020917798156042666,
    "ks_y_vs_normal": 0.0019518220846299617,
    "share_sum_exactly_zero": 0.50047,
    "baseline_ks_independent_sum_vs_normal": 0.0017646088927930625,
    "corr_x_y": -0.008226889835527693,
    "note": "baseline_* uses Z ~ N(0,1) independent of X (proposition B setting), drawn after x and w from the same generator; KS statistics use parameters estimated from the sample."
  }
}