SUBMIT A PRSUBMIT AN ISSUElast edit: Sep 16, 2025

Introducing Sub-Subnets

Historically, each subnet operates with a single incentive mechanism, a function that validators run to assign weights to miners based on the value of their work. The Sub-Subnets feature allows a subnet creator to apportion the subnet's emissions across multiple sub-subnets, each of which runs Yuma Consensus independently to evaluate the miners' performance on each of a number of distinct tasks.

Each miner receives emissions separately within each sub-subnet, so a miner's performance within one sub-subnet does not affect their rating in another, and their emissions for each epoch are summed across the sub-subnets. Validators receive dividends as a weighted sum of their performance across all sub-subnets - they cannot choose which sub-subnets to validate, and if they don't validate all sub-subnets, they receive proportionally reduced emissions. Sub-subnets don't change the total emissions to a subnet, but create a way for subnet creators to distribute those emissions to miners working on different tasks. This mechanism affords subnet creators a transparent, on-chain way to exercise fine-grained control over the work they are incentivizing, keeping miner effort focused on work that is most needed at a time.

Each sub-subnet has its own:

• Weight matrix: Each validator sets weights for each miner on each of the subnet's sub-subnets.
• Independent emissions: Since they depend on weights set by validators, a miner's emissions in each sub-subnet are independent.
• Transparent on-chain data: All sub-subnet configurations and the flow of emissions are visible on-chain.
• Emission distribution: Subnet creators can control what percentage of total emissions goes to each sub-subnet using the sudo_set_subsubnet_emission_split extrinsic.

Takeaways

1. Same Validators, Same Stake: All validators participate in all sub-subnets within a subnet with identical stake weights.
2. Same Miners: All miners registered on a subnet can participate in any or all of its sub-subnets.
3. Owner-Controlled Proportions: The holder of the subnet creator key sets the emission distribution among sub-subnets.
4. Separate Yuma Consensus: Each sub-subnet runs its own consensus to determine miner rankings.

What Should Stakers Know?

Core Impact:

• No change to your staking mechanics: Your stake is delegated to a validator on a subnet, and applies across all sub-subnets equally.
• Same total emissions: The subnet's total emissions remain unchanged - sub-subnets only redistribute these emissions internally among miners and validators.
• Transparent allocation: All emission proportions are visible on-chain, so you can see exactly how subnet owners are distributing emissions.

What This Means for Your Strategy:

• No immediate action required: Your existing staking strategy doesn't need to change
• Enhanced monitoring: You may want to track sub-subnet performance to understand subnet health
• Risk assessment: Factor in sub-subnet design when evaluating subnet quality
• Community oversight: Use transparency to hold subnet owners accountable for fair emission distribution

What Should Miners Know?

Automatic Participation:

• No separate registration: When you register for a subnet, you are eligible to participate in any of its sub-subnets
• Same UID across all sub-subnets: You use the same UID for all sub-subnets within a subnet

Performance Tracking:

• Independent scoring: Your performance is independent in different subnets, e.g. sub-subnet 0 doesn't affect your rating in sub-subnet 1.
• Separate incentive columns: You'll see individual incentive amounts for each sub-subnet in metagraph data.
• Cumulative emissions: Your total emissions = sum of emissions from all sub-subnets where you participate.

What Should Validators Know?

Core Changes

• Separate weight setting: You must set weights independently for each sub-subnet.
• Independent evaluation: Each sub-subnet requires separate assessment according to its specific criteria.
• Separate Yuma Consensus: Each sub-subnet runs its consensus algorithm independently to determine rankings.
• Same stake weight: Your stake weight is identical across all sub-subnets - no additional stake required.
• Weighted dividend calculation: Your dividends are calculated as a weighted sum of your performance across all sub-subnets. If you don't validate on all sub-subnets, you will receive proportionally reduced emissions.

Operational Changes

1. Evaluation Workload:

• Multiple assessments: You must evaluate miners separately for each sub-subnet's tasks
• Different criteria: Each sub-subnet may have distinct evaluation standards

2. Data Structure Changes:

• Two-dimensional weights: Weights are now set for each miner on each subnet.
• Separate incentive tracking: Each sub-subnet tracks incentives independently
• Extended metagraph: New columns for sub-subnet weights and incentives

What Should Subnet Creators/Developers Know?

Core Changes

• Emission distribution: You can control what percentage of total emissions goes to each sub-subnet using the sudo_set_subsubnet_emission_split extrinsic. When the number of sub-subnets is set, the emission distribution is reset to an even split, but you can set it again with custom proportions.

  info

  The sudo_set_subsubnet_emission_split extrinsic accepts an optional vector parameter. If the parameter is None, the distribution is set to an even split. When it's not None, it reflects the proportion of emissions each sub-subnet gets. The proportion is calculated as value / 65535. For example, in a subnet with two sub-subnets and vector [13107, 52428], sub-subnet 0 gets 20% and sub-subnet 1 gets 80%.

• Incentive mechanism design: You define the specific tasks and evaluation criteria for each sub-subnet

• Transparent configuration: All sub-subnet settings are visible on-chain for community oversight

• Single subnet slot: No need to register multiple subnets for multiple competitions

• Immediate sub-subnet number setting: The number of sub-subnets is set immediately when changed.

• Rate limiting: Subnet owners can set the number of sub-subnets once per 7200 blocks to prevent frequent changes.

tip

Ensure proportions sum to 100% when setting them, or the request will be rejected.

Example Emissions Split

For each subnet, the subnet creator keeps 18% of emissions, 41% is allocated to miners, and 41% to validators and their stakers, unless the subnet creator has reduced their take. Of the 41% that goes to miners and validators, here is an estimated emission distribution across three sub-subnets for each 100 $\tau$ earned on the subnet:

• Sub-subnet 0 (60%): 100 $\tau$ _.41 _ .6 = 24.6
• Sub-subnet 1 (30%): 100 $\tau$ _.41 _ .3 = 12.3
• Sub-subnet 2 (10%): 100 $\tau$ _.41 _ .1 = 4.1

Setting Custom Proportions

To achieve the above distribution, the subnet owner would submit the sudo_set_subsubnet_emission_split extrinsic with the vector [39321, 19660, 6554] (calculated as 60% × 65535, 30% × 65535, 10% × 65535).

Note that a miner who excels in sub-subnet 0 but performs poorly in others might receive more emissions than a miner who performs moderately across all sub-subnets, depending on the emission proportions and their relative performance.

On-Chain Data Structure

Sub-subnets extend the existing metagraph with additional columns:

UID | Hotkey | Stake | Sub-subnet 0 Weights | Sub-subnet 1 Weights | Sub-subnet 0 Incentive | Sub-subnet 1 Incentive
-----|--------|-------|---------------------|---------------------|----------------------|----------------------
123  | 5ABC...| 1000  | [0.3, 0.2, 0.1...] | [0.1, 0.4, 0.2...] | 0.05 τ               | 0.02 τ
456  | 7DEF...| 800   | [0.2, 0.3, 0.2...] | [0.2, 0.3, 0.1...] | 0.03 τ               | 0.04 τ

Backward Compatibility

• Existing subnets continue with only one sub-subnet (sub-subnet 0) collecting all emissions by default
• All existing API calls default to sub-subnet 0
• No breaking changes to current functionality