Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 12623

Questions related to design, implementation, and analysis of programming languages. NOT for questions about how to program, which are off-topic on this site.

1 vote
2 answers
305 views

How is it that programs can be identified with partial functions for programming language se...

I was reading about denotational semantics Broadly speaking, denotational semantics is concerned with finding mathematical objects called domains that represent what programs do. For example, pro …
Charlie Parker's user avatar
0 votes

How is it that programs can be identified with partial functions for programming language se...

The point is to express what a piece "means"/semantics. To define what it means we map syntax **at a given state ** (that takes in a state $\sigma$) to a mathematical object. This mathematical object …
Charlie Parker's user avatar
0 votes

How does one formally show that two lambda functions are $\alpha$ equivalent?

My confusion was that the definition is not that there exists a variable name such that the two functions are equal (which I believe is a better definition, probably equivalent to the one provided). I …
Charlie Parker's user avatar
2 votes
1 answer
144 views

How do we show $\lambda x . x (\lambda y .y) \equiv_{\alpha} \lambda y.y (\lambda x . x)$ in...

How do we show $$\lambda x . x (\lambda y .y) \equiv_{\alpha} \lambda y.y (\lambda x . x)$$? I was going through the slides here and it asked to do the above but by page 16 of the slides we have not …
Charlie Parker's user avatar
1 vote
1 answer
58 views

What are $(S,\Sigma)$-CCCs?

I was reading this and I was trying to understand the definition of $(S,\Sigma)$-CCC. The first requirement says: a mapping [[_]] : S → |C|, associating some object [[s]] ∈ |C| to any s ∈ S; w …
Charlie Parker's user avatar
2 votes
1 answer
72 views

What is the denotation for identifiers?

I am trying to understand what is the domain for denotational semantics. Right now the way I understand denotational semantics is that given some syntax of a program that maps to some mathematical ob …
Charlie Parker's user avatar
2 votes
4 answers
695 views

How does one formally show that two lambda functions are $\alpha$ equivalent?

I was going through the following slides and I wanted to show the following: $$ \lambda x. x \equiv_{\alpha} \lambda y . y$$ formally. They define a an $\alpha$-conversion on page 15 as follows: $$ …
Charlie Parker's user avatar
2 votes
2 answers
110 views

How does one show $(\lambda x . (\lambda y.x))yx \equiv_{\beta} y$ in lambda calculus?

I wanted to show: $$ (\lambda x . (\lambda y.x))yx \equiv_{\beta} y $$ the definition of beta equivalence is on page 17 of these notes. I did a few attempts but got different things like $x$. I thi …
Charlie Parker's user avatar
3 votes
2 answers
318 views

Why does the denotational semantics for a while loop have a existence quantifier?

I was going through these notes and they have the following operator on partial functions: $$ \mathcal F^{k}(\bot)(\sigma) = \left\{ \begin{array}{ll} \alpha( [\![s]\!]\sigma ) & [\![b]\!]\sigm …
Charlie Parker's user avatar
0 votes
0 answers
125 views

Why is Combinatorial Sketching for Finite programs possible?

I was reading Combinatorial Sketching for Finite Programs and wanted to understand why synthesis of the sketching language was possible/feasible. As far as I understand a partial program is transfor …
Charlie Parker's user avatar
2 votes
1 answer
810 views

What is the definition of a redex and what are they for in programming languages literature?

I saw the word "redex" in the context of proramming language theory/semantics in 2018 and now when I was reading a neurosymbolic research paper (machine learning with neural nets + symbolic algorithms …
Charlie Parker's user avatar
3 votes
1 answer
338 views

Proper algorithm for resolving ambiguity in grammars via enforcing associativity and precede...

I was told there is a algorithm that always resolves ambiguity for grammars that have issues with precedence and associativity. I know ambiguity in general is undecidable, so I only want to resolve th …
Charlie Parker's user avatar
5 votes
1 answer
134 views

What does $ \forall \alpha_1, \dots , \alpha_n . \tau $ mean formally as a type?

I was learning about polymorphic types but I couldn't understand the notation, can someone explain it means (context cs421 UIUC): $$ \forall \alpha_1, \dots , \alpha_n . \tau $$ its supposed to be a …
Charlie Parker's user avatar
2 votes
2 answers
89 views

Are type variables really only used in mathematical conversation about types?

Are type variables really only used in mathematical conversation about types? i.e. are type variables (meta-variables that only contain the type classification label) only exist in proofs for types bu …
Charlie Parker's user avatar
3 votes
Accepted

Why is the assignment rule the way it is in Hoare Logic?

So after reading and thinking about it more this is my explanation (thanks software foundations): The key confusion for me seems to be the meaning of $P[e/x]$ (replaces every free instance of x with …
Charlie Parker's user avatar

15 30 50 per page