This paper presents an approach for compressing litho hotspot pattern library that complies with general purpose pattern matching engine. This approach incorporates two techniques to achieve optimal pattern reduction. The first technique excludes polygons outside the optical diameter to reduce numerical noise related to a square ambit which artificially may affect a hotspot location. The second technique determines the common geometrical structures between patterns and inserts adaptive edge tolerance constraints for each individual pattern. The performance of the resulting compressed patterns is then compared to that of running the complete library of exact matches using an optimized exact pattern matching engine (OEPME). The results indicate that compression rates giving number of compressed patterns in the order of hundreds can achieve better performance than running an optimized exact pattern matcher for the whole library while maintaining the original quality of results.