Questions tagged [semantics]

Semantics formally describe the meaning of some syntax.

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6
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3answers
12k views

Call by value-result vs. call by reference?

From my Googling, it appears that call by value-result is similar to call by reference in that it changes values in the caller, but it's different in that the changes don't take place until the callee ...
10
votes
2answers
418 views

Is there a canonical definition of “pure” function?

StackOverflow pointed me here, so the question might be a bit in a layman's terms. Wikipedia defines pure functions as In computer programming, a function may be described as a pure function if ...
33
votes
1answer
9k views

Difference Between Small and Big-step Operational Semantics

What's the fundamental difference(s) between small and big-step operational semantics? I'm having a hard time grasping what it is and the motivation for having the two.
20
votes
3answers
3k views

When are two simulations not a bisimulation?

Given a labelled transition system $(S,\Lambda,\to)$, where $S$ is a set of states, $\Lambda$ is a set of labels, and $\to\subseteq S\times\Lambda\times S$ is a ternary relation. As usual, write $p \...
18
votes
2answers
3k views

What is this fraction-like “discrete mathematics”–style notation used for formal rules?

In the paper "A Conflict-Free Replicated JSON Datatype", I encountered this notation for formally defining "rules": What is this notation called? How do I read it? For example: the ...
8
votes
1answer
314 views

Formally describing a new domain specific programming language

I am about to implement a domain specific language for representation of social learning conventions. Part of the implementation is a formal description of a language - its 'calculus', symbols and ...
6
votes
2answers
825 views

Are syntax and semantic just 2 structures such that one is a model of the other?

The syntax of a language is a structure. The semantic of a language is a structure. The semantic of a language is a model of its syntax. And that's all ? The duality syntax/semantic is just model ...
5
votes
0answers
79 views

What is a “model” of lambda calculus?

I know about the concept of the "model" of a logical proposition in the context of mathematical logic: It is a mathematical structure in which that proposition is true. However, it's not clear to me ...
5
votes
2answers
3k views

Static scope and dynamic scope

I am perpetually confused when it comes to static scoping and dynamic scoping and their differences and Wikipedia isn't of any help, so here's my question: Given the following pseudo code in a ...
5
votes
3answers
1k views

Hoare triple for assignment P{x/E} x:=E {P}

I am trying to understand Hoare logic presented at Wikipedia, Hoare logic at Wikipedia Apparently, if I understand correctly, a Hoare triple $$\{P\}~ C ~\{Q\}$$ means if P just before C, then Q ...
5
votes
1answer
233 views

The definition of weakest precondition for a non-deterministic language

In the classical IMP language, the definition of weakest precondition is: definition "wp c Q s ≡ ∃t. (c,s) ⇒ t ∧ Q t" This is stating that from state s, after ...
4
votes
1answer
625 views

Denotational semantics of expressions with side effects

I'm doing revision for a module on programming language semantics and I'm having trouble understanding the introduction of side-effects in expressions. We assume a standard syntax for arithmetic ...
3
votes
1answer
74 views

What is the significance of ⟨B, s⟩ -> ⟨B', s'⟩ as the initial rule in this question about small-step semantics?

Revising for an exam and I'm trying to get to grips with operational semantics. Here's the exam question that prompted me posting this: Exam Question: We add to the language $\mathsf{SIMP}$ two new ...
0
votes
1answer
138 views

Strategy to create a testbed and gold standard

I need to create a correct evaluation of the method I'm proposing. The problem is that in the field I'm working on there is no benchmark that I can use for this purpose. On the other hand, my method ...