Intuition: Want to avoid too large of a policy update
- Smaller policy updates more likely to converge to optimal
- Falling "off the cliff" might mean it's impossible to recover
How we solve this: Measure how much policy changes w.r.t. previous, clip ratio to removing incentive to go too far.
![{\displaystyle [1-\varepsilon ,1+\varepsilon ]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/3d27a87f682ea40f872ca300adcb690abd0a0b26)