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johnbender

2,559 karmajoined 18 năm trước
github: https://github.com/johnbender

twitter: https://twitter.com/johnbender

writing: http://johnbender.us

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johnbender
·13 giờ trước·discuss
It depends on what “confirmed identical” means. Most compilers (or translators as you like) only guarantee that the output program represents a subset of the behaviors of the input program so it could be that subset is the “safe as in Rust” subset.
johnbender
·3 tháng trước·discuss
I’m confused by the calculus example and I’m hoping someone here can clarify why one can’t state the needed assumptions for roughed out theory that still need to be proven? That is, I’m curious if the critical concern the article is highlighting the requirement to “prove all assumptions before use” or instead the idea that sometimes we can’t even define the blind spots as assumptions in a theory before we use it?
johnbender
·4 tháng trước·discuss
In principle (and we hope in practice) the person is still responsible for the consequences of running the code and so it remains important they can read and understand what has been generated.
johnbender
·5 tháng trước·discuss
You have identified the crux of the problem, just like mathematics writing down the “right” theorem is often half or more of the difficulty.

In the case of digital systems it can be much worse because we often have to include many assumptions to accommodate the complexity of our models. To use an example from your context, usually one is required to assume some kind of fairness to get anything to go through with systems operating concurrently but many kinds of fairness are not realistic (eg strong fairness).
johnbender
·5 tháng trước·discuss
Compilers don’t do this error free of course BUT if we want them too we can say what it means for a compiler to be correct very directly _one time_ and have it be done for all programs (see the definition for simulation in the CompCert compiler). This is a major and meaningful difference from AI which would need such a specification for each individual application you ask it to build because there is no general specification for correct translation from English to Code.
johnbender
·5 tháng trước·discuss
Sure!

The first is an attempt to provide a semantics for activity diagrams as constraints on a state machine and thereby allow folks to specify correctness properties for the state machine using a visual language. Existing work on semantics for activity diagrams already exists but doesn’t come with tooling in the way that temporal logic does (https://arxiv.org/pdf/1409.2366)

The second is an attempt to fix a long standing problem with state machine specification languages. While many support composition operators (parallel and/or nesting) none of them come with strong theorems about when temporal properties proven about constituent elements will remain valid in the composite.
johnbender
·5 tháng trước·discuss
FM day job:

Interpretation of SysML activity diagrams as temporal logic for use with state machine specifications.

Module system for state machine with scoping, ownership type system and attendant theorems to carry proofs of LTL properties about individual parts forward after composition.
johnbender
·5 tháng trước·discuss
https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/line...

Experimental and of course one can debate whether Haskell is mainstream but I figured it merits a mention.
johnbender
·6 tháng trước·discuss
At the outset the article rather bizarrely casts the subject circumstances as a matter of government incompetence in its design and execution of an identification standard as opposed to the reality it then reports on which is DHS tripping over itself to justify unlawful detention of US citizens without cause.