> For the complete documentation index, see [llms.txt](https://devs.novanet.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://devs.novanet.xyz/jolt-atlas-zkml/onnx/tensor-instructions/lookups.md).

# Lookups

Lookup instructions require their logic to have some structure to apply the prefix-suffix sumcheck, as described in Appendix A of [Proving CPU Executions in Small Space](https://eprint.iacr.org/2025/611). That is:

* The lookup table must have an MLE that is efficiently evaluable by the verifier. The `JoltLookupTable` trait encapsulates this MLE.
* The lookup index can be split into a prefix and suffix, such that MLEs can be evaluated independently on the two parts and then recombined to obtain the desired lookup entry.
* Every prefix/suffix MLE is efficiently evaluable (constant time) on Boolean inputs.

JOLT Atlas reuses some of the instruction from the original JOLT codebase and adds new ones applying the same paradigm.