# alpha_high (/docs/hyperparameters/alpha-high)

`alpha_high` is the ceiling of the per-pair bonds EMA rate when [`liquid_alpha_enabled`](/docs/hyperparameters/liquid-alpha-enabled) is on. Pairs whose weights deviate strongly from consensus approach this rate, so their bonds move fastest. Subnet owners tune it to decide how quickly a bold, off-consensus position translates into bonds; validators care because it caps how fast conviction can build or unwind.

## How it works [#how-it-works]

Each epoch, `alpha_sigmoid` (`pallets/subtensor/src/epoch/run_epoch.rs`) maps a pair's deviation from consensus into the EMA rate:

```
alpha = alpha_low + sigmoid(diff) × (alpha_high − alpha_low)
```

The deviation is `weight − consensus` when a validator is raising its bond, or `bond − weight` when lowering it (both clamped to 0..1). As deviation grows past 0.5 the sigmoid saturates toward 1 and alpha approaches `alpha_high`; the result is clamped into the `alpha_low`..`alpha_high` window. The resulting per-pair matrix drives the bonds EMA `B(t) = alpha × W + (1 − alpha) × B(t−1)` in `mat_ema_alpha`. Defaults are (45875, 58982) — 0.7 and 0.9 of `u16::MAX`.

Validation in `do_set_alpha_values`: liquid alpha must already be enabled (`LiquidAlphaDisabled`), and `alpha_high` must be at least 1638 (`u16::MAX / 40` ≈ 0.025), else `AlphaHighTooLow`. `alpha_low` may not exceed it.

<HyperparamLiquidAlpha focus="alpha_high" />

## Reading and setting [#reading-and-setting]

```
btcli sudo get --netuid N --name alpha_high
```

Stored as u16 (65535 = 1.0); the CLI accepts the raw integer or a 0..1 fraction with a decimal point:

```
btcli sudo set --netuid N --name alpha_high --value 0.9
```

On chain, [`alpha_low`](/docs/hyperparameters/alpha-low) and `alpha_high` live in one storage value set by a single `sudo_set_alpha_values` call. The CLI reads the current pair and resubmits it with only `alpha_high` changed, so the other side is preserved.

## Related [#related]

[`alpha_low`](/docs/hyperparameters/alpha-low), [`alpha_sigmoid_steepness`](/docs/hyperparameters/alpha-sigmoid-steepness), [`liquid_alpha_enabled`](/docs/hyperparameters/liquid-alpha-enabled), [`bonds_moving_avg`](/docs/hyperparameters/bonds-moving-avg), [`yuma3_enabled`](/docs/hyperparameters/yuma3-enabled)