{
  "handle": "BackwardChain",
  "mechanism": "Goal-First Decomposition: Start from desired end-state, recursively identify prerequisites. For each prerequisite, ask \"what must be true for this to hold?\" until reaching known facts or actionable steps. Execution order is reverse of discovery order. A goal-directed form of {{deduction}} — derives required antecedents from the desired consequent. Structures the {{chain_of_thought}} in reverse chronological order, linking the desired future state to present preconditions.",
  "gloss": "Goal-driven reasoning from target to preconditions",
  "failure_modes": [
    "Infinite Regression: The precondition chain never terminates because base facts are missing."
  ],
  "invariants": [
    "Causal Sufficiency: Step(T) must be sufficient condition for Step(T+1)",
    "Goal Anchoring: {{chain}} must start at DesiredEndState",
    "Leaf nodes must be actionable or known-true."
  ],
  "preconditions": [
    "Goal state clearly defined.",
    "Domain has prerequisite structure.",
    "Knowledge base queryable."
  ],
  "postconditions": [
    "Execution plan produced OR goal proven unachievable.",
    "{{plan}} steps in executable order.",
    "All prerequisites satisfied."
  ],
  "_meta": {
    "tier": 1,
    "ring": 2,
    "supersedes": [
      "sema:BackwardChain#mh:SHA-256:04841f7ca3e84925caa3e0480d39467e3707e7fdf8eefe3650177c25fbd4c43b",
      "sema:BackwardChain#mh:SHA-256:4f06546167f2ac9d04fadbbb0c8033f2638d91d8c319b346f4b3c735a819dfab",
      "sema:BackwardChain#mh:SHA-256:9ff877cde5b5de2a850c5fade17d56a9da5fd5330cbba29f59953e6934de8cde"
    ],
    "path": [
      "Mind",
      "Reasoning"
    ]
  },
  "sema_id": "sema:BackwardChain#mh:SHA-256:92c0e4700ff6bc202bd16dc4c77fd0b826605462cdc30d8b4230c36f61df0bb3",
  "sema_ref": "BackwardChain#92c0",
  "sema_stub": "92c0",
  "dependencies": {
    "references": {
      "chain": "sema:Chain#mh:SHA-256:3ba084dba5cf36bbdd43d03306c187ca75a2e3f448b555e257c26aab9b71c4fb",
      "chain_of_thought": "sema:ChainOfThought#mh:SHA-256:27ad1f2386f58e1f9e1983c97f6dbeb8f1345e1d9b9e00af30871b97d21e0c95",
      "deduction": "sema:Deduction#mh:SHA-256:b9a034741d2b404c84277fed48ce23edb262b9a9f3166ae27fdb431d006dd6ec",
      "plan": "sema:Plan#mh:SHA-256:246db278c5db286fcd78d824d85054fafb3348565ef584599b63900000c43b32"
    }
  },
  "sema_layer": "Mind",
  "sema_category": "Reasoning",
  "used_by": {}
}