Comment by rramadass

> As I understand it now it's about saying what the value of a particular language construct should be (e.g. when evaluated), as opposed to whether the construct is allowed/part of the language (syntax). Is that intuition wrong?

Your intuition is right. It falls under what is called "Operational Semantics" (https://en.wikipedia.org/wiki/Operational_semantics) There are other aspects of looking at it i.e. "Denotational Semantics", "Axiomatic Semantics", "Algebraic Semantics" etc. which are more mathematical. The submitted book talks about all of them.

For more background, you might want to look at Alan Parkes book Introduction to Languages, Machines, and Logic.

The basic idea is that Symbolic Logic allows you to express Strings (sentences containing words) constructed from an Alphabet (set of symbols for that language) as "Programs" (which are valid i.e. meaningful strings in that language) which can then be interpreted by a Abstract Machine we call a Computer.