# Formal system Books that work as introduction to mathematics, either begin by introducing sets since set theory, namely ZFC, is currently considered as the foundational theory of math (from which all of mathematics can be derived), or they first touch on a formal (propositional) logic system since it's the simplest formal system. On the one hand sets need fomal logic as they utilize logical symbols as soon as the set notation is introduced. By the way, the view that logic comes before math, i.e. that math is part of logic is called logicism. propositional -> predicate -> higer-order logic systems -> ... ↓ ↓ set set set set set -> relations -> orders -> functions -> ... lamda calculus || SK combinatorics || PRF --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://mandober.gitbook.io/math-debrief/100-fundamentals/terms/formal-system.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.