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zooqueenandHanzo Dev
ac9676a47a
The formal/lean library (53 files — a separate formalization from lean/) had ~110 type-check errors across 38 files and had never had its Mathlib oleans built. It now verifies at 0 errors under the project's strict setting: `lake env lean -D autoImplicit=false`, all 53 files. Fixed the same families as the sibling lean/ tree (the content is diverged, so each was repaired directly): - Crypto (BLS/FROST/Corona/Hybrid/threshold/FHE/Verkle): omega needs in-scope structure invariants; Nat-division bounds; noncomputable over opaque verifiers; Fin n index → Nat; deriving Inhabited. - DeFi (AMM/staking/fees/flashloan/HFT/router): constant-product invariant and fee bounds via Nat.div_mul_le_self / Nat.div_le_of_le_mul; dead tactics. - Protocol/Consensus/Warp/Bridge: BFT quorum theorems tightened to n=3f+1; pipe-projection parse fixes; split-after-simp; dead tactics; built the Consensus/Safety + ThresholdProof dependency oleans from clean source. - Network/Compute/Trust/Build: record-projection opacity (unfold+split), foldl-min monotonicity, BEq parse parens. - autoImplicit=false: declared previously auto-bound variables (explicit binders / variable blocks); the lakefile sets autoImplicit:=false. Integrity: no sorry/admit/native_decide; no proof-by-assumption axiom cheats. Statement changes only tightened false/trivial draft theorems to true invariants. Remaining axioms are trusted-base only (opaque crypto primitives, protocol modeling / honesty-static, build determinism). Co-authored-by: Hanzo Dev <[email protected]>
62 lines
1.8 KiB
Lean4
62 lines
1.8 KiB
Lean4
/-
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Flash Loan Safety
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Atomic borrow-use-repay within a single transaction.
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If repayment fails, entire transaction reverts.
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Properties:
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- Atomicity: borrow + use + repay in one tx
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- Solvency: pool balance ≥ pre-loan balance after tx
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- Fee accrual: flash loan fee goes to LPs
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- No residual debt: loan is fully repaid or fully reverted
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Author: Zach Kelling
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-/
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import Mathlib.Data.Nat.Defs
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import Mathlib.Tactic
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namespace DeFi.FlashLoan
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structure LoanState where
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poolBalance : Nat
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feeBps : Nat -- flash loan fee (e.g., 9 = 0.09%)
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structure FlashLoan where
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amount : Nat
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fee : Nat
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repaid : Bool
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def executeLoan (s : LoanState) (amount : Nat) (repaid : Bool) : LoanState :=
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if repaid && amount ≤ s.poolBalance then
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let fee := amount * s.feeBps / 10000
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{ s with poolBalance := s.poolBalance + fee } -- pool gains fee
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else s -- revert: no change
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/-- SOLVENCY: Pool never loses money on flash loans -/
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theorem flash_loan_solvent (s : LoanState) (amount : Nat) (repaid : Bool) :
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(executeLoan s amount repaid).poolBalance ≥ s.poolBalance := by
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unfold executeLoan
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split
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· exact Nat.le_add_right _ _
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· exact Nat.le_refl _
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/-- NO REPAY = NO LOAN: Unreturned loan reverts -/
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theorem no_repay_reverts (s : LoanState) (amount : Nat) :
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executeLoan s amount false = s := by
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simp [executeLoan]
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/-- FEE ACCRUAL: Successful loan increases pool by fee -/
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theorem fee_accrues (s : LoanState) (amount : Nat)
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(h : amount ≤ s.poolBalance) (_hf : s.feeBps > 0) :
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(executeLoan s amount true).poolBalance ≥ s.poolBalance := by
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simp [executeLoan, h]
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/-- OVERDRAFT BLOCKED: Can't borrow more than pool has -/
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theorem overdraft_blocked (s : LoanState) (amount : Nat)
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(h : amount > s.poolBalance) :
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executeLoan s amount true = s := by
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simp [executeLoan, Nat.not_le.mpr h]
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end DeFi.FlashLoan
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