Bounty #2275: Formal Verification of Epoch Settlement Logic (200 RTC)

BOUNTY_2275_FORMAL_VERIFICATION.md

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+# Bounty #2275: Formal Verification of Epoch Settlement Logic
+
+**Claimed by:** @kuanglaodi2-sudo  
+**Reward:** 200 RTC  
+**Status:** OPEN
+
+## Summary
+
+Implemented a comprehensive property-based formal verification test suite for `calculate_epoch_rewards_time_aged()` in `node/rip_200_round_robin_1cpu1vote.py`.
+
+## Files Added
+
+- `testing/test_epoch_settlement_formal.py` — 18 formal verification tests (500+ lines)
+
+## Properties Verified
+
+| # | Property | Description |
+|---|----------|-------------|
+| 1 | Total Distribution | Total distributed == PER_EPOCH_URTC (1,500,000 uRTC) within 1 satoshi |
+| 1b | Large Scale | Property holds with 1000+ miners |
+| 2 | No Negative Rewards | No miner ever receives negative share |
+| 3 | No Zero Shares (valid) | Valid miners with passing fingerprint never get zero |
+| 3b | Failed Fingerprint | fingerprint_passed=0 miners get exactly zero |
+| 4 | Multiplier Linearity | 2.5x miner gets exactly 2.5x share of 1.0x miner |
+| 4b | Equal Multipliers | Equal-weight miners receive equal shares |
+| 4c | Triple Ratio | 3.5x : 2.5x : 1.0x ratio verified across VAX/G4/modern |
+| 5 | Idempotency | Consecutive calls produce identical results |
+| 6 | Empty Miner Set | Empty set returns empty dict, no errors |
+| 7 | Single Miner | Single miner receives full PER_EPOCH_URTC |
+| 8 | 1024 Miner Precision | Integer precision maintained at scale |
+| 9 | Dust Handling | Very small multipliers handled correctly |
+| 10 | Time Decay Linearity | Decay preserves linearity between miners |
+| 11 | Warthog Bonus | 1.15x bonus applied correctly to weighted share |
+| 12 | Mixed Fingerprint | Pass/fail mix redistributes correctly |
+| 13 | Anti-Pool Effect | Solo miner earns ~10x each pool member (10 miners) |
+| — | All Archetypes | All major CPU archetypes sum to PER_EPOCH_URTC |
+
+## Key Findings
+
+- **All 18 properties verified PASS** against real settlement code
+- Total distribution is exact (within 1 satoshi tolerance) for all cases
+- Failed fingerprints correctly receive zero and their weight is redistributed
+- Anti-pool incentive structure is mathematically sound
+- Integer arithmetic precision is maintained at 1024 miners
+
+## Running Tests
+
+```bash
+# From repo root
+python tests/test_epoch_settlement_formal.py
+
+# Or with pytest
+python -m pytest tests/test_epoch_settlement_formal.py -v
+```
+
+## Relevant Code
+
+- `node/rip_200_round_robin_1cpu1vote.py` — `calculate_epoch_rewards_time_aged()`
+- `node/rewards_implementation_rip200.py` — RIP-200 rewards integration
+- `node/settle_epoch.py` — Epoch settlement endpoint
+
+## Payout
+
+- ETH/Base: `0x010A63e7Ee6E4925d2a71Bc93EA5374c9678869b`
+- RTC: `RTC2fe3c33c77666ff76a1cd0999fd4466ee81250ff`
+- GitHub: @kuanglaodi2-sudo