The important part is at the end of the article: "For those interested in building a stronger foundation in logic, the Open Logic Project provides excellent free educational resources on propositional and predicate logic, formal proof systems, and other topics such as modal logic and set theory - all targetted towards a non-mathematical audience."
I don't get it. Isn't this what compilers are for? So I don't have to rewrite my code in an equivalent but stupider way just to get a marginal performance gain.
etbebl 6 days ago [-]
I think what you're missing is that the premise of a hardware bug is just a frame story for a lesson in manipulating logical statements, which is the main point.
tantalor 5 days ago [-]
Okay, it's just incredibly contrived.
You might as well replace "hardware bug" with "a wizard put a curse on the OR operator" or "the president put a tariff on OR imports", and it would be more believable.
bbaron63 6 days ago [-]
Presumably, the compiler is not aware of the hardware bug in the OR operation, so it won't do any transforms to avoid using the OR operation.
tantalor 6 days ago [-]
Okay so... then patch the compiler? This is basic stuff.
spartanatreyu 6 days ago [-]
If it were "basic stuff", then you probably weren't using a high performance compiler to begin with.
> At every place X in the following expression, introduce a boolean negation if there isn’t one (or, equivanently remove one if there is), and
I think it should read:
At every place X in the following expression, introduce a boolean negation if there isn’t one and remove one if there is, and
Maybe even better:
At every place X in the following expression, introduce a boolean negation.
If you get two concecutive NOT's, they can be removed.
Next, I don't see how
timespent <= duration
is the negation of
duration > time_spent
?
hoppp 6 days ago [-]
My first thought was to rewrite it without any or and operation.
just return early from if statement.
If user is blacklisted return access denied;
If account is expired return access denied;
If no conditions match return access granted;
Wouldn't that be more effective?
ChilledTonic 6 days ago [-]
You are touching on an inherent truth in TFL, which is that there are nearly infinite equivalent statements for any logical sentence.
The idea for the article was to make a real example of logical equivalence, as books on the subject stay pretty abstract. - like others have mentioned, in the real world there are smarter choices to be made.
The code blocks’ font size varies line by line on mobile. Hint: set it to be smaller than the body text size because monospace fonts tend to be a bit larger than proportional ones.
ChilledTonic 6 days ago [-]
You've discovered a CSS issue that I did not notice for seven years.
Thanks.
The issue was that for some reason, different types of code had different font size settings.
Rendered at 22:38:19 GMT+0000 (Coordinated Universal Time) with Vercel.
https://openlogicproject.org/
You might as well replace "hardware bug" with "a wizard put a curse on the OR operator" or "the president put a tariff on OR imports", and it would be more believable.
I think it should read:
At every place X in the following expression, introduce a boolean negation if there isn’t one and remove one if there is, and
Maybe even better:
At every place X in the following expression, introduce a boolean negation. If you get two concecutive NOT's, they can be removed.
Next, I don't see how
is the negation ofIf user is blacklisted return access denied; If account is expired return access denied; If no conditions match return access granted;
Wouldn't that be more effective?
The idea for the article was to make a real example of logical equivalence, as books on the subject stay pretty abstract. - like others have mentioned, in the real world there are smarter choices to be made.
Thanks.
The issue was that for some reason, different types of code had different font size settings.