module_mint

mint module

Introduction

The mint module is responsible for creating tokens in a flexible way to reward the validators who participate in the proof of stake consensus process (see also the distribution module). It is also designed in a way to bring a balance between market liquidity and staked supply.

Overview

Network parameters

Below are all the network parameters for the mint module:

• "blocks_per_year" - The expected number of blocks being produced per year;

• "goal_bonded" - Goal of bonded token in percentage;

• "inflation_max" - Maximum annual inflation rate;

• "inflation_min" - Minimum annual inflation rate;

• "inflation_rate_change" - Maximum annual change in inflation rate;

• "mint_denom" - Token type being minted.

The target annual inflation rate is recalculated for each previous cycle. The inflation is also subject to a rate change (positive or negative) depending on the distance from the desired ratio ("goal_bonded"). The maximum rate change possible is defined to be "inflation_rate_change" per year, where the annual inflation is capped as between "inflation_min" and "inflation_max".

Parameters explained

"goal_bonded"

Goal of bonded token in percentage (also called staking ratio), the changes of the reward and the inflation rate related to this parameter can be summarized as follows cases:

• If the staking ratio is below the "goal_bonded" , the inflation rate will increase until reaching a maximum upper bound ("inflation_max");

• If the staking ratio is equal to "goal_bonded", the inflation rate will stay constant;

• If the staking ratio is above the "goal_bonded", it will decrease until reaching a minimum lower bound "inflation_min").

"inflation_rate_change"

Maximum annual change in inflation rate, represents the maximum percentage by which the inflation rate can change in a year.

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Emissions and supply of $CRO

The current emissions and supply of $CRO and its emission projections can be easily queried directly from URLs, as described in this section.

How inflation rate is calculated

The magnitude of the rate of change of the inflation rate is controlled by an additional factor, which is the ratio between the current bonded ratio with the "goal_bonded", the inflation rate is updated at the end of every block accordingly to the following formula:

Inflation Rate = min(max(params.InflationMin, currentInflation + ((1 - bondedRatio / params.GoalBonded) * params.InflationRateChange / params.BlocksPerYear)), params.InflationMax)

Or simply, when the inflation rate within the maximum and the minimum bounds

current inflation + ((1 - bondedRatio / params.GoalBonded) * params.InflationRateChange / params.BlocksPerYear)),

as

This function then updates the current inflation rate by adding the inflationRateChange to it. Finally, the function checks that the updated inflation rate is within the range defined by the InflationMin and InflationMax parameters, and returns the resulting inflation rate.

How emissions are calculated

Annual provisions

The emission of the Cronos POS Chain is controlled by the inflation rate and the total supply of $CRO. New $CRO tokens are minted at each block and distributed as block rewards to delegators. The inflation rate determines the amount of $CRO emitted to delegators at each block, with emissions being distributed as staking rewards according to the Proof-of-Stake consensus mechanism.

The annualized quantity of $CRO emitted is called Annual Provisions. It can be calculated based on the inflation rate with:

Annual provisions = Inflation rate * Total supply of CRO

At any point, the inflation, in annualized percentage increase of CRO supply, can be queried from https://rest.mainnet.cronos-pos.org/cosmos/mint/v1beta1/inflation.

This can be seen in the following code in the Cosmos SDK:

m.Inflation.MulInt(totalSupply)

Easy to use endpoints to query $CRO emissions

• The current value of annual provisions of CRO can be queried at any time at this endpoint.
• The total supply of CRO can be queried at any time at this endpoint

Note: These numbers are provided in basecro, where 1 CRO = 10^8 basecro on the Cronos POS chain.

• Annualized emissions can also be seen on the Blockchain Explorer at https://cronos-pos.org/explorer under "Events" of each block.
• This annualized emission value can be derived into a per-block value (see Block provisions), using the block per year value provided by the following endpoint: https://rest.mainnet.cronos-pos.org/cosmos/mint/v1beta1/params

Block provisions

To calculate the number of $CRO emitted to delegators at each block, we need to divide the Annual Provisions by the expected number of blocks per year (blocks_per_year, an be queried at any time at this endpoint)

The resulting number is called the "Block Provision":

Reward per block = Block Provision = Annual provisions / Expected blocks per year

This can be seen in the following code in the CosmosSDK:

m.AnnualProvisions.QuoInt(math.NewInt(int64(params.BlocksPerYear)))

Total and Circulating Supply of $CRO

• The Total Supply refers to the total amount of $CRO that has been created on Cronos POS chain;

• The Circulating Supply refers to the total supply minus the amount stored in the "burn address", which has effectively been taken out of circulation by community burn governance proposals, i.e.

Circulating Supply = Total supply - [$CRO balance held in the burn address]

Easy to use endpoints to query $CRO supplies:

• The current total supply of $CRO can be obtained here.
• The current circulating supply of $CRO can be obtained here.
• The current burned amount of $CRO can be obtained here.

Note - This number is provided in basecro, where 1 CRO = 10^8 basecro on the Cronos POS chain.

• Total burned amount and progress can be found in the Cronos Burninfo page.

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mint module: Queries

Queries

Query the current minting annual provisions value

We can query the current minting annual provisions value, for example:

curl

$ curl -X GET "https://rest.mainnet.crypto.org/cosmos/mint/v1beta1/annual_provisions"
{ "annual_provisions": "100346483960386394.920000000000000000" }

implies that the current minting annual provisions will be 100346483960386394 basecro ( i.e. 1,003,464,839 CRO)

chain-maind cli

$ chain-maind query mint annual-provisions 
100346483960386394

Query the current minting inflation value

We can query the current minting inflation value, for example:

curl

$ curl -X GET "https://rest.mainnet.crypto.org/cosmos/mint/v1beta1/inflation"
{
  "inflation": "0.037000000000000000"
}

implies that the inflaction rate is 3.7%

chain-maind cli

 $ chain-maind query mint inflation
  0.037000000000000000

implies that the inflaction rate is 3.7%

Query the current minting parameters

We can query the current query parameters by

curl

$ curl -X GET "https://rest.mainnet.crypto.org/cosmos/mint/v1beta1/params"

{
  "params": {
    "mint_denom": "basecro",
    "inflation_rate_change": "0.100000000000000000",
    "inflation_max": "0.037000000000000000",
    "inflation_min": "0.012000000000000000",
    "goal_bonded": "0.600000000000000000",
    "blocks_per_year": "6311520"
  }
}c

chain-maind cli

$ chain-maind query mint params --output json | jq

  {
    "mint_denom": "basetcro",
    "inflation_rate_change": "0.100000000000000000",
    "inflation_max": "0.037000000000000000",
    "inflation_min": "0.012000000000000000",
    "goal_bonded": "0.600000000000000000",
    "blocks_per_year": "6311520"
  }

---

Appendix

gov module: Network Parameters and configuration

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

	blocks_per_year	goal_bonded	mint_denom
Type	string (uint64)	string (dec)	string
Higher	More expected blocks per year	Higher target bonding ratio	N/A
Lower	Less expected blocks per year	Lower target bonding ratio	N/A
Constraints	Value has to be a positive integer	Value has to be less or equal to 1	N/A
Sample configuration	5256000 (5,256,000 blocks)	0.66 (66%)	basecro

	inflation_max	inflation_min	inflation_rate_change
Type	string (dec)	string (dec)	string (dec)
Higher	Higher ceiling for the inflation rate	Higher floor for the inflation rate	Higher yearly rate of change to the inflation
Lower	Lower ceiling for the inflation rate	Lower floor for the inflation rate	Lower yearly rate of change to the inflation
Constraints	Value has to be less or equal to 1	Value has to be less or equal to 1	Value has to be less or equal to 1
Sample configuration	0.02 (2%)	0.01 (1%)	0.01 (1%)