# Subnet Hyperparameters

In addition to miners and validator code, each subnet has a set of parameters (often referred to as hyper parameters) that define how it will interact with the bittensor network.

## Taostats

Each subnet has a Hyperparameters option:

## Using CLI

To see the parameters of a subnet, use the `btcli su get`

**or** `btcli s hyperparameters`

Here are example parameters from Subnet 15 at the time of writing:

```
btcli sudo get
Enter netuid [0/1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/24/25/26/27/28/29/30/31/32] (0): 15
Subnet Hyperparameters - NETUID: 15 - finney
HYPERPARAMETER VALUE
rho 10
kappa 32767
immunity_period 1000
min_allowed_weights 1
max_weight_limit 65535
tempo 360
min_difficulty 18446744073709551615
max_difficulty 18446744073709551615
weights_version 0
weights_rate_limit 100
adjustment_interval 360
activity_cutoff 5000
registration_allowed False
target_regs_per_interval 1
min_burn 1
max_burn 100000000000
bonds_moving_avg 900000
max_regs_per_block 1
serving_rate_limit 50
max_validators 64
adjustment_alpha 58000
difficulty 18446744073709551615
```

# Hyperparameter descriptions

**rho**: 10 for all subnets. Rho (p) is calculated based on the network's target inflation and actual neuron staking. It adjusts the emission rate of the TAO token to balance the network's economy and dynamics. The formula for Rho is defined as: p = (Staking_Target / Staking_Actual) * Inflation_Target. Here, Staking_Target and Staking_Actual represent the desired and actual total stakes in the network, while Inflation_Target is the predefined inflation rate goal.**kappa**: 32767 for all subnets. Kappa (κ) is used in the calculation of neuron ranks, which determine their share of network incentives. It is derived from the softmax function applied to the inter-neuronal weights set by each neuron. The formula for Kappa is: κ_i = exp(w_i) / Σ(exp(w_j)), where w_i represents the weight set by neuron i, and the denominator is the sum of exponential weights set by all neurons. This mechanism ensures a normalized and probabilistic distribution of ranks based on relative weights.**Immunity Period**: This parameter defines the duration during which new neurons are protected from certain network penalties or restrictions. (At 12 s/block, 1000 blocks is ~ 3.3 minutes.)**Min Allowed Weights**: The minimum number of UIDs a subnet validator must set weights on, before the subnet validator is allowed to set weights on the blockhain.**Max Weight Limit**: Highest weight value that can be set by a validator. This is a float value.**Tempo**: Cadence of updates, in blocks.**mix/max difficulty**: Obsolete - no longer used.**weights version**: Sets the minimum version of validator code that a validator can use (and still set weights).**weights rate limit**: time (in blocks) that a validator may update weights.**adjustment_interval**: Time (in blocks) after which the node registration cost is re-evaluated. If the number of actual registrations that occurred in the last`adjustment_interval`

is higher than the`target_regs_per_interval`

, then the blockchain will raise the recycle register cost, by increasing the`min_burn`

value by a certain amount, in order to slow down the actual registrations and bring them back to`target_regs_per_interval`

value.**activity cutoff:**- Expressed in number of blocks. If a subnet validator has not set weights on the blockchain for
`activity_cutoff`

duration, then the Yuma Consensus will consider this subnet validator as offline, i.e., turned off. The weights of this subnet validator are considered too old to be useful. The weights of this subnet validator slowly lose their impact over time and eventually will no longer be considered for consensus calculation.

- Expressed in number of blocks. If a subnet validator has not set weights on the blockchain for
**registration_allowed**: When a subnet updates or there is an issue - the subnet owner may pause registrations to allow for all miners and validators to update their servers without the risk of deregistration.**target_regs_per_interval**: Number of nodes that can be registered per epoch. In the example above, just one node can be registered per interval.**min_burn/max_burn**: Node registration costs (in rao - 1e-9 tao). The max listed above is 100 tao.**serving_rate_limit**: Determines how often you can change your node's IP address on the blockchain. Expressed in number of blocks. Applies to both subnet validator and subnet miner nodes. Used when you move your node to a new machine.**Bonds Moving Avg**:- This parameter controls how fast bonds will decay in the entire subnet. This is a unitless number. This number has a direct impact on subnet validator. The faster the bonds decay the quicker a subnet validator will lose its dividends after the subnet validator is out of the
`activity_cutoff`

.

If this`bonds_moving_avg`

value is low, then the moving average of the bonds will decay slowly. This will allow the subnet validator to become active again, start setting new weights and start earning new bonds.

If this`bonds_moving_avg`

value is high, then bonds in the subnet decay quickly. As a result, a subnet validator who has fallen out of the`activity_cutoff`

and hence is running the risk of being viewed as "turned off", may not be able to become active again.

- This parameter controls how fast bonds will decay in the entire subnet. This is a unitless number. This number has a direct impact on subnet validator. The faster the bonds decay the quicker a subnet validator will lose its dividends after the subnet validator is out of the
**Max Validators**: The number of validator slots available in the subnet.**Adjustment alpha:**Larger numbers smooth the registration burn costs epoch to epoch.

Updated about 1 month ago