> For the complete documentation index, see [llms.txt](https://docs.moduluszk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.moduluszk.io/core-concepts-cont..md).

# Core Concepts cont.

### Proofs and state transitions

On Modulus a state transition is a claim, and the chain admits claims only with evidence. A transaction proposes a change to state, names the predicates governing that state, and carries a proof that those predicates are satisfied by the proposed change. The validator checks the proof. Nothing executes; conditions are checked.