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Weights are the scores the subnet publishes to Bittensor. Emissions are how the subnet splits influence across challenges. This page explains how raw challenge scores become one normalized vector.

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The problem the aggregator solves

Several challenges run at once, each producing its own raw hotkey scores on its own scale. Bittensor expects a single vector indexed by UID. The aggregator bridges the two.

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Step 1: normalize each challenge’s weights

For one challenge, the raw hotkey -> weight map is cleaned and normalized. Non-finite values and values at or below zero are dropped, then the rest are scaled to sum to 1. 
def normalize_weights(raw: dict[str, float]) -> dict[str, float]:
    cleaned = _clean_weights(raw)
    total = sum(cleaned.values())
    if total <= 0:
        return {}
    return {hotkey: value / total for hotkey, value in cleaned.items()}

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Step 2: normalize emissions across challenges

Each active challenge carries an emission share (emission_percent). The aggregator clamps negatives to zero and normalizes the shares of active challenges so they sum to 1. If nothing is active, every share is zero.

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Step 3: combine into a UID vector

The aggregator walks every active challenge. For each one it multiplies that challenge’s normalized emission share by each hotkey’s normalized weight, and accumulates per hotkey: 
for hotkey, weight in normalize_weights(result.weights).items():
    hotkey_scores[hotkey] += emission * weight
It then maps each hotkey to its Bittensor UID and sums per UID, with two rules:
  • A hotkey with no known UID is skipped.
  • UID 0 is skipped.
Finally it normalizes the UID scores to sum to 1, ordered by UID. If the total is zero, it falls back to assigning all weight to UID 0.
The practical takeaway: your reward depends on both how well you score within a challenge and that challenge’s emission share. A strong score in a small-share challenge contributes less than the same relative score in a large-share one.

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What gets published

The aggregator emits a FinalWeights value with aligned uids and weights lists, plus the surviving per-hotkey weights. This is the vector the on-chain submitter reads from the master and submits to Bittensor at each epoch.

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Next

Incentive mechanism

Why the subnet is built to reward real work.

How the subnet works

See where aggregation sits in the full flow.