How to calculate Euler's health score
===

## Health score

To avoid to be liquidated, keep $HealthScore$ greater than 1.0 .

Generally $HealthScore$ is denoted as
$$
HealthScore = {RiskAdjustedCollateral \over RiskAdjustedLiability}
$$

### Evaluate risk-adjusted collateral

Here assume a user deposit a single asset and leverage its position.

Let $a^c$ denote the balance of collateral and $s^c$ denote the self-collateralized balance of collateral.
Let $f^c$ denote the collateral factor of a asset, $f^b$ denote its borrow factor and $f^s$ denote the collateral factor of a self-collateralized asset (called self-collateralized factor).

Risk-adjusted collateral is calculated as
$$
v^c = f^c[a^c -{s^c \over f^s}] + s^c \tag{1}
$$
where $f^c \leqq f^s$.

### References
https://github.com/euler-xyz/euler-contracts/blob/6086c6e585f03ceb3365a4e011dc892af96f1de8/contracts/modules/RiskManager.sol#L317-L329

### Evaluate risk-adjusted liability

Risk-adjusted liability is calculated as
$$
v^b = {a^b - s^b \over f^b} + s^b \tag{2}
$$

where self-collateralized part of any asset have always 1.0 borrow factor. $s^b$ is always equal to $s^c$ ??

> In Euler self-collateralized part of any asset has always 0.95 collateral factor and 1.0 borrow factor.

for example,

deposits 1000 USDC and mints 9000 USDC. normal CF of USDC is 0.9

now collateral 10000 USDC and liability 9000 USDC.

so, risk adjusted collateral = (10000 - 9000/0.95) * 0.9 + 9000 * 0.95 = 9023
risk adjusted liability  = 9000*1

### References

https://github.com/euler-xyz/euler-contracts/blob/6086c6e585f03ceb3365a4e011dc892af96f1de8/contracts/modules/RiskManager.sol#L331-L334