{
  "handle": "Fermi",
  "mechanism": "Decomposed Estimation: break unknown quantity into factors you can {{estimate}}. Multiply factors. Accept order-of-magnitude accuracy. Example: \"pianos in Chicago\" = population × household fraction × piano-owning fraction. Errors often cancel across factors. It invokes {{decompose}} to break an unknown quantity into estimable sub-factors.",
  "gloss": "Estimation via decomposition",
  "failure_modes": [
    "Correlated Error Stacking: If all sub-estimates are biased in the same direction (e.g., all optimistic), the errors compound rather than cancel."
  ],
  "invariants": [
    "Error Cancellation: Overestimation in sub-factors tends to cancel underestimation",
    "Geometric Mean: Final estimate is geometric mean of bounds"
  ],
  "parameters": [
    {
      "name": "confidence_interval",
      "type": "Percentage",
      "range": "[50%, 95%]",
      "description": "Target coverage of true value"
    },
    {
      "name": "decomposition_depth",
      "type": "Integer",
      "range": "[2, 6]",
      "description": "Estimation chain length"
    }
  ],
  "_meta": {
    "tier": 2,
    "ring": 2,
    "supersedes": [
      "sema:Fermi#mh:SHA-256:1e06d04bfff04954ad09852a7a4b1b583acc76c431dc926b4afe3cce5abfe210",
      "sema:Fermi#mh:SHA-256:128b7131810fba03748bcc5dce657248d5547beeb23e87750cd76e6e59a80bd5",
      "sema:Fermi#mh:SHA-256:964a2d4f8166deefb544d347da4f4c36b2c32885bb24f2f3e36cd3361638c9c2",
      "sema:Fermi#mh:SHA-256:688559c783f162aee4fc61fd380bd30094219d76a844a6a9efce9ae1feeaf622"
    ],
    "path": [
      "Mind",
      "Reasoning"
    ]
  },
  "sema_id": "sema:Fermi#mh:SHA-256:f206e74f19af3eb55825b02c2192779a627ddff7b1c465a09d73431b863232db",
  "sema_ref": "Fermi#f206",
  "sema_stub": "f206",
  "dependencies": {
    "composes_with": {
      "decompose": "sema:Decompose#mh:SHA-256:69942e7e0dcdc7781144da58c8f09b2e8a17c247be435dadf3325cb0d0bbb22b",
      "estimate": "sema:Estimate#mh:SHA-256:3bacc0606623a0603b271a835b54157c2e86389c4282af86d88cd1ddd9ecf917"
    }
  },
  "sema_layer": "Mind",
  "sema_category": "Reasoning",
  "used_by": {}
}