emerged. Floyd, in the lead to his 1967 paper Assigning meanings to programs, writes: A semantic definition of a programming language, in our approach, is founded on a syntactic definition. It must specify which of the phrases in a syntactically correct program represent commands, and what conditions must be imposed on an interpretation in the neighborhood of each command. Linguistics In linguistics, semantics is the subfield that studies meaning. Semantics can address meaning at the levels of words, phrases, sentences, or larger units of discourse. Two of the fundamental issues in the field of semantics are that of compositional semantics (which pertains on how smaller parts, like words, combine and interact to form the meaning of larger expressions, such as sentences) and lexical semantics (the nature of the meaning of words). Other prominent issues are those of context and its role on interpretation, opaque contexts, ambiguity, vagueness, entailment, and presuppositions. Several disciplines and approaches have contributed to the often-contentious field of semantics. One of the crucial questions which unites different approaches to linguistic semantics is that of the relationship between form and meaning. Some major contributions to the study of semantics have derived from studies in the 1980–1990s in related subjects of the syntax–semantics interface and pragmatics. The semantic level of language interacts with other modules or levels (like syntax) in which language is traditionally divided. In linguistics, it is typical to talk in terms of "interfaces" regarding such interactions between modules or levels. For semantics, the most crucial interfaces are considered those with syntax (the syntax–semantics interface), pragmatics, and phonology (regarding prosody and intonation). Disciplines and paradigms in linguistic semantics Formal semantics Formal semantics seeks to identify domain-specific mental operations which speakers perform when they compute a sentence's meaning on the basis of its syntactic structure. Theories of formal semantics are typically floated on top of theories of syntax, such as generative syntax or combinatory categorial grammar, and provided a model theory based on mathematical tools, such as typed lambda calculi. The field's central ideas are rooted in early twentieth century philosophical logic, as well as later ideas about linguistic syntax. It emerged as its own subfield in the 1970s after the pioneering work of Richard Montague and Barbara Partee and continues to be an active area of research. Conceptual semantics This theory is an effort to explain properties of argument structure. The assumption behind this theory is that