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Mint

The mint module is responsible for creating tokens in a flexible way to reward validators, provide funds for IXO governance, and pay Impact Reawrds according to IXO tokenomics.

The module is also responsible for reducing the token creation and distribution by a set period until it reaches its maximum supply (see reduction_factor and reduction_period_in_epochs)

The module uses time basis epochs supported by the epochs module.

Contents

  1. Concept
  2. State
  3. Begin Epoch
  4. Parameters
  5. Events
  6. Queries

Concepts

The x/mint module is designed to handle the regular printing of new tokens within a chain. The design taken within IXO is to

  • Mint new tokens once per epoch (default one day)
  • To have a "Reductioning factor" every period, which reduces the number of rewards per epoch. (default: period is 3 years, where a year is 365 epochs. The next period's rewards are 2/3 of the prior period's rewards)

Reduction factor

This is a generalization over the Bitcoin-style halvenings. Every 3 years, the number of rewards issued per epoch will reduce by a governance-specified factor, instead of a fixed 1/2. So RewardsPerEpochNextPeriod = ReductionFactor * CurrentRewardsPerEpoch). When ReductionFactor = 1/2, the Bitcoin halvenings are recreated. We default to having a reduction factor of 2/3 and thus reduce rewards at the end of every 3 years by 33%.

The implication of this is that the total supply is finite, according to the following formula:

Total Supply = InitialSupply + EpochsPerPeriod * { {InitialRewardsPerEpoch} / {1 - ReductionFactor} }

State

Minter

The Minter is an abstraction for holding current rewards information.

type Minter struct {
    EpochProvisions ixomath.Dec   // Rewards for the current epoch
}

Params

Minting Params are held in the global params store.

LastReductionEpoch

Last reduction epoch stores the epoch number when the last reduction of coin mint amount per epoch has happened.

Begin-Epoch

Minting parameters are recalculated and inflation is paid at the beginning of each epoch. An epoch is signaled by x/epochs

NextEpochProvisions

The target epoch provision is recalculated on each reduction period (default 3 years). At the time of the reduction, the current provision is multiplied by the reduction factor (default 2/3), to calculate the provisions for the next epoch. Consequently, the rewards of the next period will be lowered by a 1 - reduction factor.

EpochProvision

Calculate the provisions generated for each epoch based on current epoch provisions. The provisions are then minted by the mint module's ModuleMinterAccount. These rewards are transferred to a FeeCollector, which handles distributing the rewards per the chain's needs. This fee collector is specified as the auth module's FeeCollector ModuleAccount.

Network Parameters

The minting module contains the following parameters:

Key Type Example
mint_denom string "uixo"
genesis_epoch_provisions string (dec) "500000000"
epoch_identifier string "day"
reduction_period_in_epochs int64 730
reduction_factor string (dec) "0.6666666666666"
distribution_proportions.staking string (dec) "0.9"
distribution_proportions.impact_rewards string (dec) "0.1"
distribution_proportions.community_pool string (dec) "0.0"
weighted_impact_rewards_receivers array [{"address": "ixoxx", "weight": "1"}]
minting_rewards_distribution_start_epoch int64 10

Below are all the network parameters for the mint module:

  • mint_denom - Token type being minted
  • genesis_epoch_provisions - Amount of tokens generated at the epoch to the distribution categories (see distribution_proportions)
  • epoch_identifier - Type of epoch that triggers token issuance (day, week, etc.)
  • reduction_period_in_epochs - How many epochs must occur before implementing the reduction factor
  • reduction_factor - What the total token issuance factor will reduce by after the reduction period passes (if set to 66.66%, token issuance will reduce by 1/3)
  • distribution_proportions - Categories in which the specified proportion of newly released tokens are distributed to
    • staking - Proportion of minted funds to incentivize staking IXO
    • impact_rewards - Proportion of minted funds to pay into impact rewards pools for distribution according to tokenomics
    • community_pool - Proportion of minted funds to be set aside for the community pool
  • weighted_impact_rewards_receivers - Addresses that impact rewards will go to. The weight attached to an address is the percent of the impact rewards that the specific address will receive
  • minting_rewards_distribution_start_epoch - What epoch will start the rewards distribution to the aforementioned distribution categories

Notes

  1. mint_denom defines denom for minting token - uixo
  2. genesis_epoch_provisions provides minting tokens per epoch at genesis.
  3. epoch_identifier defines the epoch identifier to be used for the mint module e.g. "weekly"
  4. reduction_period_in_epochs defines the number of epochs to pass to reduce the mint amount
  5. reduction_factor defines the reduction factor of tokens at every reduction_period_in_epochs
  6. distribution_proportions defines distribution rules for minted tokens, when the impact rewards address is empty, it distributes tokens to the community pool.
  7. weighted_impact_rewards_receivers provides the addresses that receive impact rewards by weight
  8. minting_rewards_distribution_start_epoch defines the start epoch of minting to make sure minting start after initial pools are set

Events

The minting module emits the following events:

End of Epoch

Type Attribute Key Attribute Value
mint epoch_number {epochNumber}
mint epoch_provisions {epochProvisions}
mint amount {amount}


Queries

params

Query all the current mint parameter values

query mint params

::: details Example

List all current min parameters in json format by:

ixod query mint params -o json | jq

An example of the output:

{
	"mint_denom": "uixo",
	"genesis_epoch_provisions": "821917808219.178082191780821917",
	"epoch_identifier": "day",
	"reduction_period_in_epochs": "365",
	"reduction_factor": "0.666666666666666666",
	"distribution_proportions": {
		"staking": "0.900000000000000000",
		"impact_rewards": "0.100000000000000000",
		"community_pool": "0.000000000000000000"
	},
	"weighted_impact_rewards_receivers": [
		{
			"address": "ixo1n8yrmeatsk74dw0zs95ess9sgzptd6thgjgcj2",
			"weight": "1.000000000000000000"
		}
	],
	"minting_rewards_distribution_start_epoch": "1"
}

:::

epoch-provisions

Query the current epoch provisions

query mint epoch-provisions

::: details Example

List the current epoch provisions:

ixod query mint epoch-provisions

As of this writing, this number will be equal to the genesis-epoch-provisions. Once the reduction_period_in_epochs is reached, the reduction_factor will be initiated and reduce the amount of IXO minted per epoch. :::

Appendix

Current Configuration

mint module: Network Parameter effects and current configuration

The following tables show overall effects on different configurations of the mint related network parameters:

mint_denom epoch_provisions epoch_identifier
Type string string (dec) string
Higher N/A Higher inflation rate Increases time to reduction_period
Lower N/A Lower inflation rate Decreases time to reduction_period
Constraints N/A Value has to be a positive integer String must be day, week, month, or year
Current configuration uixo 821917808219.178 (821,9178 IXO) day
reduction_period_in_epochs reduction_factor staking
Type string string (dec) string (dec)
Higher Longer period of time until reduction_factor implemented Reduces time until maximum supply is reached More epoch provisions go to staking rewards than other categories
Lower Shorter period of time until reduction_factor implemented Increases time until maximum supply is reached Less epoch provisions go to staking rewards than other categories
Constraints Value has to be a whole number greater than or equal to 1 Value has to be less or equal to 1 Value has to be less or equal to 1 and all distribution categories combined must equal 1
Current configuration 365 (epochs) 0.666666666666666666 (66.66%) 0.250000000000000000 (25%)
pool_incentives developer_rewards community_pool
Type string (dec) string (dec) string (dec)
Higher More epoch provisions go to pool incentives than other categories More epoch provisions go to developer rewards than other categories More epoch provisions go to community pool than other categories
Lower Less epoch provisions go to pool incentives than other categories Less epoch provisions go to developer rewards than other categories Less epoch provisions go to community pool than other categories
Constraints Value has to be less or equal to 1 and all distribution categories combined must equal 1 Value has to be less or equal to 1 and all distribution categories combined must equal 1 Value has to be less or equal to 1 and all distribution categories combined must equal 1
Current configuration 0.450000000000000000 (45%) 0.250000000000000000 (25%) 0.050000000000000000 (5%)