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Questions tagged [semantics]

Semantics formally describe the meaning of some syntax.

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6 votes
3 answers
14k 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 ...
Tootsie Rolls's user avatar
10 votes
2 answers
524 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 ...
Andrey Shchekin's user avatar
42 votes
2 answers
13k 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.
Simon Morgan's user avatar
20 votes
3 answers
4k 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 \...
Dave Clarke's user avatar
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19 votes
2 answers
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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 ...
natevw's user avatar
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8 votes
1 answer
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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 ...
Edmon's user avatar
  • 297
7 votes
2 answers
1k 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 ...
François's user avatar
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5 votes
1 answer
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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 ...
user1868607's user avatar
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5 votes
3 answers
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 ...
zell's user avatar
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5 votes
0 answers
136 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 ...
user56834's user avatar
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5 votes
2 answers
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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 ...
mellartach's user avatar
4 votes
1 answer
867 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 ...
user2320239's user avatar
3 votes
1 answer
88 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 ...
notywq's user avatar
  • 31
0 votes
1 answer
150 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 ...
Caleb's user avatar
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