Compositional semantics is a linguistic and philosophical approach used to understand the meaning of sentences and phrases within a language. It operates on the principle that the meaning of a complex expression can be derived from the meanings of its constituent parts and the rules that combine them. This approach plays a pivotal role in formal semantics and the study of how language conveys meaning.

Key principles and aspects of compositional semantics include:

1. Compositionality: At its core, compositional semantics adheres to the principle of compositionality, which posits that the meaning of a whole linguistic expression is determined by the meanings of its individual parts and the way they are structured or combined. In other words, the meaning of a sentence is the result of combining the meanings of its words and the syntactic relationships between them.

2. Syntax and Semantics: Compositional semantics considers both the syntactic structure (how words are arranged) and the lexical semantics (the meaning of individual words) to derive the meaning of a sentence or phrase. It involves mapping syntactic structures to semantic representations.

3. Truth-Conditional Semantics: A common approach within compositional semantics is truth-conditional semantics. This approach associates sentences with truth conditions, indicating under what circumstances a sentence is true or false. It often employs formal logic to represent meaning.

4. Semantic Ambiguity: Compositional semantics addresses the issue of semantic ambiguity, where a single sentence can have multiple interpretations or meanings. By analyzing the constituents and their possible combinations, it seeks to disambiguate sentences.

5. Principle of Compositionality: The principle of compositionality is expressed as follows: "The meaning of a complex expression is a function of the meanings of its parts and their mode of combination." This principle guides the systematic analysis of language.

6. Scope and Quantification: Compositional semantics is particularly valuable in dealing with scope and quantification, which involve understanding how words like "every," "some," "all," and "none" affect the meaning of sentences when combined with other expressions.

7. Formal Models: To operationalize compositional semantics, formal models and systems like lambda calculus, Montague grammar, and type theory are often used to represent the structure and meaning of language.