> For the complete documentation index, see [llms.txt](https://docs.fast.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fast.xyz/proof-of-proof-archived/core-technologies/formal-semantics-and-the-k-framework.md).

# Formal Semantics & the K Framework

An easy way to understand the K framework is to see it as a meta-language that can implement or define other programming languages.

In the K framework, a language definition consists of two modules: one defining the syntax and the other defining the semantics using rewrite rules.

* Syntax: Defined using BNF grammar.
* Semantics: Defined using rewrite rules that specify how a program executes.

A configuration is a term that contains all the necessary information to execute programs, including the code and the program state.

Formal semantics are defined using rewrite rules that describe how configurations change during program execution.

The K framework provides a suite of tools, including, [parsers](https://en.wikipedia.org/wiki/Parsing), [interpreters](https://en.wikipedia.org/wiki/Interpreter_\(computing\)), [model checkers](https://en.wikipedia.org/wiki/Model_checking), [symbolic execution engines](https://en.wikipedia.org/wiki/Symbolic_execution) and [formal program verifiers](https://en.wikipedia.org/wiki/Formal_verification).

For a detailed description of formal semantics and the K framework, please see our [K section](https://docs.pi2.network/k/overview).

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