[Metamath] Re: Area of a triangle (was: Help with beginning to contribute to set.mm)

2019-06-04 Thread Benoit
On Tuesday, June 4, 2019 at 11:15:03 AM UTC+2, Jon P wrote: > > Benoit I like your way of using barycentric coordinates to express the > interior of the triangle, that is quite elegant. I am not sure how to fit > it into this scheme though, > The points "inside" the tr

Re: [Metamath] How to do substitutions in Metamath?

2019-06-02 Thread Benoit
x A $. $d x ps $. sbcie.1 $e |- A e. _V $. sbcie.2 $e |- ( x = A -> ( ph <-> ps ) ) $. sbcie $p |- ( [. A / x ]. ph <-> ps ) $= Benoit > > My experience is that implicit substitution is more easy to work with. > _ > Thierry > > > -- You received this

[Metamath] Re: Metamath book cover

2019-06-02 Thread Benoit
The ideal solution would be to use MetaPost to design a real $\Aleph_0$... or maybe to use an existing one (see https://tex.stackexchange.com/questions/170476/how-to-get-aleph-and-beth-symbols-in-similar-font#170494 for various fonts) ? Benoit -- You received this message because you

[Metamath] Re: Replacing $d with F/ and F/_

2019-05-28 Thread Benoit
On Tuesday, May 28, 2019 at 9:25:47 PM UTC+2, Giovanni Mascellani wrote: > > Hi! I think there is a general trick to replace a $d x A or $d x ph$ > condition in a theorem with the corresponding F/_ x A or F/ x ph, but I > do not remember it. Can anybody help me? > > (in this specific case, I

Re: [Metamath] Replacing $d with F/ and F/_

2019-05-28 Thread Benoit
Using the replacements I gave above yielded the proof: ${ $d z A $. $d x y z $. $d z ph $. sbcex2f.1 $e |- F/_ x A $. $( Move existential quantifier in and out of class substitution. (Contributed by NM, 21-May-2004.) (Revised by NM, 18-Aug-2018.) $) sbcex2f $p |- ( [.

Re: [Metamath] Removing dependencies on some logically redundant axioms

2019-05-28 Thread Benoit
Sorry, I misread Mario's post. It looks like we agree on F/2 from an intuitionitic point of view. Then why not take the same definition for set.mm ? In any case, I will not do this right now and I would first write a draft in my mathbox before making any change. -- You received this message

Re: [Metamath] Removing dependencies on some logically redundant axioms

2019-05-28 Thread Benoit
On Tuesday, May 28, 2019 at 6:02:38 PM UTC+2, Mario Carneiro wrote: > > I'm okay with the alternative df-bj-nf definition. If the use of the > definition E. is undesirable, here are some more alternatives: > > $a |- ( F/1 x ph <-> A. x ( ph -> A. x ph ) ) > $a |- ( F/2 x ph <-> ( E. x ph -> A. x

[Metamath] Removing dependencies on some logically redundant axioms

2019-05-28 Thread Benoit
. I'll be interested in your comments, especially on adopting the alternate definition for non-freeness. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send

[Metamath] Area of a triangle (was: Help with beginning to contribute to set.mm)

2019-06-03 Thread Benoit
| \exists a, b, c \in \R_{\geq 0}, a + b + c = 1 and X = a A + b B + c C \} This generalizes to all simplices in any dimension (starting with dimension 0). By the way, I think that in your (Thierry) description, you got the opposite sign for F and your S is actually a parallelogram. Benoi

Re: [Metamath] Help with beginning to contribute to set.mm

2019-06-02 Thread Benoit
Maybe you can also begin a new thread, with a subject like "Area of a triangle". Thanks, Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email

Re: [Metamath] How to do substitutions in Metamath?

2019-06-02 Thread Benoit
age like Metamath) I think that it is often possible to avoid "[ / ]-substitutions" (are they the ones called "implicit substitutions"?) by modifying your proof a bit, and use "explicit substitution" instead (typically with steps like "x = A -> ( ph <-> ps )").

[Metamath] Re: Why is ~ 4syl discouraged?

2019-06-14 Thread Benoit
like exponential time complexity in the number of $e-hypotheses of the theorem to minimize with, and 4syl has four $e-hypotheses... I agree that it is a useful theorem, but you can see manually if it is worth to launch a "minimize 4syl/override": if your proof already uses 3syl and

Re: [Metamath] The theorem itexp (soon to be itgpow) (was: Help with beginning to contribute to set.mm)

2019-06-14 Thread Benoit
lt;. x , y >. | ( <. x , y >. e. A /\ y e. C ) } > !qed::|- B e. dom area > > It looks false: what if C is not measurable ? (e.g. take A to be the unit square and C a non-measurable subset of [0,1]) > Also, why not try directly with the deduction version th

Re: [Metamath] The theorem itexp (soon to be itgpow) (was: Help with beginning to contribute to set.mm)

2019-06-15 Thread Benoit
At least, do a line break after "$=". Never use tabulations. If the line of the statement needs to be broken, then break it after operators which are "high in the parsing tree" (I don't know how to say it precisely and concisely, but you see what I mean). Benoit --

Re: [Metamath] Re: Area of a triangle (was: Help with beginning to contribute to set.mm)

2019-06-09 Thread Benoit
, reflections), so that you can then suppose that your triangle has one vertex at (0, 0), one at (a, 0) with a > 0, and the third at (b, c) with c > 0, and then its area is ac/2. Obviously, the invariance under displacements is much harder to prove, but this is the correct way to go. Beno

Re: [Metamath] The theorem itexp (soon to be itgpow) (was: Help with beginning to contribute to set.mm)

2019-06-17 Thread Benoit
. So go directly for the deduction form (unless the proof is short enough that you can prove the closed form). I think you can state more general rules like the one you wrote. For arearect and areaquad, I would say: wait until you need the deduction form. Benoit -- You received this mess

Re: [Metamath] Re: unbundling set.mm

2019-06-20 Thread Benoit
} = { z | E. x E. w ( z = <. x , w >. /\ [ w / x ] x = 2 ) } which yields, if I'm not mistaken, |- { <. x , x >. | x = 2 } = { z | E. x z = <. x , 2 >. } which is clearly false. Benoit -- You received this message because you are subscribed to the Google Groups &quo

Re: [Metamath] Re: unbundling set.mm

2019-06-20 Thread Benoit
which imply that { <. x , x >. | ph } is not a subset of the diagonal, would be going too far away from mathematical practice. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving email

Re: [Metamath] EEhil

2019-06-21 Thread Benoit
, but not on a direct product. As for the unicode symbol for the direct sum of copies of \R, I would use Mario's suggestion from a previous thread, i.e. R^() instead of R^. This would free up the symbol R^ to be used for the direct product. Benoit -- You received this message because you are subscribed

[Metamath] Re: Tweak set.mm using "A further simplification of Tarski's axioms of geometry" by Timothy Makarios?

2019-06-27 Thread Benoit
I mentionned it in https://groups.google.com/d/msg/metamath/BSOOYEw2sjU/TmHaccI5AwAJ and I think Thierry took it into account in his treatment (he was part of that discussion in the fall). Benoit On Thursday, June 27, 2019 at 3:24:45 PM UTC+2, David A. Wheeler wrote: > > The paper &quo

Re: [Metamath] Re: Metamath page on Wikipedia

2019-07-12 Thread Benoit
t; part, since it is in the Metamath book, where it belongs, and wikipedia is not a "how to" nor a substitute to the Metamath website or book. * Other sections Benoit On Friday, July 12, 2019 at 9:18:20 AM UTC+2, Jon P wrote: > > It looks like they have a s

Re: [Metamath] Re: Metamath page on Wikipedia

2019-07-14 Thread Benoit
the unity of mathematic (no 's'!). I've read big chunks of the first five books and "Lie groups and algebras" and spectral theory. It is a reference book, not a textbook or a pedagogical device. Benoit -- You received this message because you are subscribed to the Google Grou

[Metamath] Re: Bourbaki and Metamath

2019-07-14 Thread Benoit
ect is dormant, on its way, soon to be resurrected... Benoit On Sunday, July 14, 2019 at 2:48:08 PM UTC+2, fl wrote: > > > > or belonging to the sphere of influence of Germany (Banach) > > I have just noticed that Banach wrote in French in Polish reviews. So much > for the G

Re: [Metamath] Re: RFC: Mandatory definitions after constants

2019-07-02 Thread Benoit
(or even searching with ctrl+F in a text editor)? I guess this is doable in mmj2 with regular expressions? I've been a bit extreme in not overloading symbols, and defined couples of classes as (| A ,, B |) (see bj-c2uple), although the unicode symbol for ",," is "," so tha

Re: [Metamath] Help needed with unicode

2019-07-02 Thread Benoit
sponding STIX version. I'm not sure whether it is font-family: STIX2Math; src: url(STIX2Math.woff2); or a variant (e.g. STIXTwoMath). Then, we could easily compare ascii.html with ascii-STIX.html from several browsers, devices, etc. before switching. Benoit -- You received this message b

Re: [Metamath] Help needed with unicode

2019-07-01 Thread Benoit
es "text-only") than go into very intricate hard-to-maintain code in order to have a better looking symbol. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from

[Metamath] ( ph -> ( ps -> ch ) ) versus ( ( ph /\ ps ) -> ch )

2019-07-16 Thread Benoit
mpler statements, both the curried and the uncurried forms should be in set.mm. But later? Is there a "good practice", a rule of thumb? Thanks, Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and st

Re: [Metamath] Help needed with unicode

2019-07-01 Thread Benoit
is not concerned with bidirectional writing). See the STIX font project: https://github.com/stipub/stixfonts A comparison of STIX and XITS, dated from before STIX 2, but anticipating it: https://tex.stackexchange.com/questions/227216/stix-versus-xits Benoit -- You received this message because you

Re: [Metamath] Re: RFC: Mandatory definitions after constants

2019-07-02 Thread Benoit
c-statements? i.e. have blocks $c smurf $. csmurf $a class smurf $. df-smurf $a smurf = ... $. This would look more systematic. As suggested above, maybe one could also standardize the comments, for example "Extend class notation to smurf / Syntax for smurf / Define smurf, the function t

Re: [Metamath] Trying to generalize David Wheeler's Algebra helpers.

2019-08-14 Thread Benoit
s as well. In my case, I haven't tried to be systematic and haven't thought too much about the most economical way to treat these, but I used some of them to prove a formula for barycentric coordinates in ~bj-bary1. Benoit -- You received this message because you are subscribed to the Goo

[Metamath] Updates of the "us" and "us2" servers

2019-08-20 Thread Benoit
e, I think it would at least be possible that the "us" version never be the latest: when doing the update, first copy "us2" to "us", and then update "us2". Benoit -- You received this message because you are subscribed to the Google Groups "Metamath&qu

[Metamath] Re: Updates of the "us" and "us2" servers

2019-08-21 Thread Benoit
y (with travis?) that if a PR contains proof modifications, then these modifications do not add new dependencies on $a-statements? (You can see the same obsession that led me to suggest the modification of "minimize_with" to default to "no_new_axioms".) Benoit -- You rec

[Metamath] Re: ex-natded5.3i used on minimize

2019-08-31 Thread Benoit
r (PR #1068). In PR #1072, I added a comment to ex-natded5.3i to recommend use of jccir instead. I also removed the two remaining uses of ex-natded* theorems mentioned by Alexander. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To

[Metamath] Puzzle: shortest Metamath databases

2019-09-01 Thread Benoit
I obtained 40 characters (uninteresting: simply add an unrelated $v-statement to the previous ones). For "containing a correct proof and an $f-statement", I obtained 44 characters.) Benoit -- You received this message because you are subscribed to the Google Groups "Metamath&qu

[Metamath] Re: Updates of the "us" and "us2" servers

2019-08-21 Thread Benoit
old. Can the "updating schedule" for both servers be documented somewhere? Thanks, Benoit On Wednesday, August 21, 2019 at 8:47:32 AM UTC+2, Alexander van der Vekens wrote: > > Considering Norm's explanations, I think a delay of at most 3 days would > be OK. This should also be enough

[Metamath] Re: Updates of the "us" and "us2" servers

2019-08-23 Thread Benoit
to detect the modifications that are in between a "$=" and a "$." and return the associated label (which is the word immediately preceding the "$p" immediately preceding that "$="). I'm not asking that it be implemented (though if someone feels like i

[Metamath] Re: ex-natded5.3i used on minimize

2019-08-21 Thread Benoit
Alexander, can you check, using the script "scripts/min.cmd", whether the theorem "jccil" (where the conclusion is "( ph -> ( ch /\ ps ) )" ) is also worth adding? Thanks, Benoit On Wednesday, August 21, 2019 at 12:52:29 AM UTC+2, Norman Megill wrote: > >

[Metamath] Re: Infinite direct sum of RR as a Hilbert space

2019-08-05 Thread Benoit
equence A(n) does not converge, so the space is not complete." [Proof: Let B be in ( RR^() ` NN ). Therefore, B \in span(e_1, ..., e_k) for some k. Therefore, for arbitrarily large n (indeed, for all n larger than k), on has |A(n) - B| > 1/(k+1). So A(n) does not converge to B. Since B w

[Metamath] Help on mmj2 start options

2019-09-30 Thread Benoit
directory of the mm file with respect to that of the metamath program in the RunParms.txt file ? E.g. LoadFile,../../git/set.mm/set.mm Thanks, Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and s

Re: [Metamath] Re: Metamath Zero

2019-10-01 Thread Benoit
Thanks for the detailed explanations. Concerning weaker arithmetics: Is EFA the same thing as I\Delta_0 + exp ? And if I understand correctly, you say that I\Delta_0 should actually suffice ? Or maybe I\Delta_0 + \Omega_1 ? (Of course, I think PA was a wise choice for a first attempt, for

[Metamath] Re: Improved definition checking of set.mm, and df-sbc no longer an exception

2019-09-26 Thread Benoit
finitional soundness check. Dummy variables [y] are possibly free in the definiendum, and no justification is available. --- [By the way: the failure to pass the test for df-clab, df-cleq, df-clel should not be due to the obsolete axioms mentioned, but this is another matter.] Benoit -- You r

Re: [Metamath] Improved definition checking of set.mm, and df-sbc no longer an exception

2019-09-26 Thread Benoit
ly, any non-setvar dummy variable could be replaced by _V (or (/)) or T. (or F.) depending on their type. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email

[Metamath] Re: Looking for publicly-acknowledged avatars for Gource

2019-10-02 Thread Benoit
Hi David, I think my GitHub avatar was automatically generated. You may use it for the Gource visualization. Thanks, Benoît -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an

Re: [Metamath] Re: Gource video of set.mm contributions

2019-09-29 Thread Benoit
umo0 which are backups of demoted theorems placed in my mathbox.) Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to metamath+unsubscr...@googl

[Metamath] Re: Gource video of set.mm contributions

2019-09-29 Thread Benoit
of a section would be that of its first statement)? Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to metamath+unsubscr...@googlegroups.com. To view this

Re: [Metamath] Re: 'minimize_with' command in metamath.exe

2019-09-22 Thread Benoit
ery useful. It is always open on my desktop when I work on set.mm. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to metamath+unsubscr...@googl

[Metamath] Re: 'minimize_with' command in metamath.exe

2019-09-22 Thread Benoit
ibuting.md file on the mmset.html page (I'll make a proposal in my next PR). Note that the Metamath home page has a FAQ section with a question "How can I contribute to Metamath", and the answer has a link to github.com/metamath/set.mm . Granted, this is not very direct. Benoit --

[Metamath] Help needed with unicode

2019-06-30 Thread Benoit
hen I generate the html pages on my computer, the characters look fine. This might be because the fonts are not installed by default? Remark: actually, I generally use in \widehat{A} instead of \hat{A} (and similarly \overline{A} instead of \bar{A}) since I think the larger marks look better, but I ha

Re: [Metamath] Help needed with unicode

2019-06-30 Thread Benoit
not work on metamath.org where, if I understood correctly, a special set of fonts is loaded locally? Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, sen

[Metamath] Re: question about fsumshft

2019-11-03 Thread Benoit
> Therefore, I still would propose to recommend to use the form $e |- ( ( ph /\ > x = ... ) -> ... ) $. in deduction style. I agree. Plus, this is more systematic hence easier to remember. > Already existing theorems need not to be rewritten They need not but they could ! > (by the way, many

Re: [Metamath] Uniqueness of MM0 secondary parsing

2019-11-07 Thread Benoit
Thanks. Indeed, with this extended definition of left/right-associativity (that is, associativity among all operators of a given precedence, and not merely associativity of a given operator), it all makes sense and is consistent, and indeed the condition given by Mario to ensure unambiguity

Re: [Metamath] Uniqueness of MM0 secondary parsing

2019-11-07 Thread Benoit
b * c" is to be read as "( a * b ) * c", and nothing more than that. It seems that to you, there is an additional meaning: if * and + have the same precedence and are both left-associative, then " a * b + c " is to be read as " ( a * b ) + c". It seems a bit abu

Re: [Metamath] Uniqueness of MM0 secondary parsing

2019-11-14 Thread Benoit
I hope parts of this discussion will make their way into some kind of documentation, in particular the possibility to add extra parentheses and the fact that MM0 uses the term "sort" instead of "type" because the type system is voluntarily poor, and if some type theory is to be implemented,

Re: [Metamath] Uniqueness of MM0 secondary parsing

2019-11-11 Thread Benoit
Thanks for the clear explanations. I didn't know this use of the word "barb", and I see on dictionary.com "unpleasant remark". My remarks were certainly not meant to be unpleasant, and I'm interested in seeing where MM0 goes. Is it always possible to put parentheses, even where they are not

Re: [Metamath] Uniqueness of MM0 secondary parsing

2019-11-08 Thread Benoit
Thanks Giovanni. I hope Mario can also chime in on the questions in my previous message, since these are not right-or-wrong issues, but are more about balancing pros (proximity with mathematical practice) and cons (more complex parser). You write: > In you example, you definitely want "." to

[Metamath] Problem with us2 ?

2019-11-21 Thread Benoit
Hi, If I recall correctly, the us2 server is updated within 24 hours of a new merge in metamath/set.mm on github (I cannot retrieve this information). But the merge https://github.com/metamath/set.mm/pull/1261#event-2813593206 is from 20 nov. 2019 à 02:26 UTC+1 (35 hours ago at the time of

[Metamath] Re: Proven: Fourier series convergence, #76

2019-12-15 Thread Benoit
I'm also hoping for an outline of the proofs (especially the "encoding" in set.mm and the difficulties encountered). Is there a particular reason why sin, cos were used instead of exp ? Benoît -- You received this message because you are subscribed to the Google Groups "Metamath" group. To

[Metamath] Re: Proven: Fourier series convergence, #76

2019-12-15 Thread Benoit
Thanks Glauco for this outline. First, I re-ask my previous question: is there a particular reason you chose sine and cosine over the exponential function ? Like FL, I think several lemmas deserve to be in the main part. I will use your sectioning: ORDERING ON REAL NUMBERS - REAL AND

[Metamath] Re: 'minimize' runs

2019-12-17 Thread Benoit
> > The basic idea is to run 'minimize */a */n ax-*' on each proof and send > the results (in a log file) to me, without saving the proof. > Maybe add the options /VERBOSE /TIME to have all the information possible. Benoît -- You received this message because you are subscribed to the Google

Re: [Metamath] Re: CONGRATS! Alexander van der Vekens has proven the Cayley-Hamilton theorem (Metamath 100 #49, total of 72)

2019-12-12 Thread Benoit
Alexander, I'm looking at the section comment of "21.25.10.3 The Cayley-Hamilton theorem". What is the metamath label corresponding to Equation (2) ? I see that ~cramer has no theorem referencing it. I thought the natural proof of (2) would use Cramer's rule ? Thanks, Benoît -- You

Re: [Metamath] Re: [set.mm] The conditional operator for propositions

2019-12-07 Thread Benoit
On Sunday, October 6, 2019 at 12:50:37 AM UTC+2, Mario Carneiro wrote: > > It can also be used together with bitwise type logical operations, such as > df-cad and df-had. > To give an example, I added http://us.metamath.org/mpeuni/bj-cadif.html bj-cadif|- (cadd ( ph , ps , ch ) <-> if- (

Re: [Metamath] Stone-Weierstrass

2019-12-14 Thread Benoit
Indeed, it totally makes sense. Thanks. Benoit -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to metamath+unsubscr...@googlegroups.com. To view this

[Metamath] Stone-Weierstrass

2019-12-14 Thread Benoit
Prompted by the post on the proof of convergence of Fourier series, I looked at other "100" theorems and stumbled on the Stone-Weierstrass theorem. ~stowei has a dv condition on F,t. This appears to imply that stowei shows only approximability of constant functions. Similarly, ~stoweid has

[Metamath] Re: Proven: Fourier series convergence, #76

2019-12-16 Thread Benoit
> > the proofs that I followed stated the coefficients in terms of sine and > cosine. Some of them, then, proved some intermediate results using the > complex exponential form (it simplified some integral calculation), some > other sources instead kept using sine and cosine everywhere. When I

Re: [Metamath] DNS event

2019-10-24 Thread Benoit
Now that it's back to normal, I have two naive questions: 1) Isn't the purpose of mirror sites to serve as replacements when an even like this occurs ? However, during the event, it seems the mirror sites were unavailble either. Can we do something about it ? 2) Because of the event, the

Re: [Metamath] DNS event

2019-10-24 Thread Benoit
Just in case this wasn't clear enough: these were two naive questions, as I wrote. Maybe I should have written "genuinely naive" or "naively genuine" to be clearer. Anyway, thanks Norm for the explanations. Benoît On Thursday, October 24, 2019 at 10:42:11 PM UTC+2, vvs wrote: > > BTW, there

Re: [Metamath] Re: Looking for a name

2019-10-23 Thread Benoit
Actually, I would go for the biconditional, as Mario suggests, since it's always nicer to have a characterization. The useful part is indeed the forward implication, since the reverse implication is always true and obvious and easy to prove, but I think this is not a reason to keep it out of

Re: [Metamath] Re: Metamath Zero

2019-10-25 Thread Benoit
Hi Mario, That's a very nicely written paper, that shows some impressive work! It made me want to try and learn mm0. I'll have to digest your article more. I found some typos after a first reading (maybe for some of them, it is actually me misunderstanding the paper): p.4b: \bar y \sharp \bar

[Metamath] Removing dependencies on ax-13

2019-12-01 Thread Benoit
Hi all, A few months ago, after the discussion here on bundling with Mario, I experimented removing dependencies on ax-13 from many theorems. This is in my mathbox, in the section titled 21.29.4.12 Removing dependencies on ax-13 (and ax-11) (beginning with

[Metamath] Re: Removing dependencies on ax-13

2019-12-02 Thread Benoit
Thanks for your suggestions. In any case, I do not plan to move anything to the main part before the end of 2019, so we still have time to discuss. As for Jim's remarks: in your specific example, sb56 currently requires ax-13, whereas bj-equs5v (and bj-sb56) do not. But I see a shorter way to

Re: [Metamath] Re: CONGRATS! Alexander van der Vekens has proven the Cayley-Hamilton theorem (Metamath 100 #49, total of 72)

2019-11-28 Thread Benoit
As for definitions: it looks like Alexander was referring mainly to $e-statements which serve the purpose of local definitions, while David talked mainly about the $a-statements. As for the $e-statement definitions, they can serve as definitions used in the statement of the theorem, or only

Re: [Metamath] Re: Problem with us2 ?

2019-11-28 Thread Benoit
A word of caution (without being dismissive whatsoever of Wolf's great work): shorter proof (or, more precisely, proof with fewer steps) does not always mean simpler proof, or easier-to-understand proof. This is why I am thankful that Wolf keeps *OLD versions (which should be checked before

Re: [Metamath] Re: Problem with us2 ?

2019-11-28 Thread Benoit
On Thursday, November 28, 2019 at 2:18:19 PM UTC+1, ookami wrote: > > The rules by which a proof is considered shorter were explained to me by > Norm about 10 years ago: First look at the size of the encoding of the > compressed proof, not taking the references into account. On tie, count the >

[Metamath] [set.mm] The conditional operator for propositions

2019-10-05 Thread Benoit
Hi all, A few months ago, I added the "conditional operator for propositions" to my mathbox (currently Section 21.29.1.6, beginning at http://us2.metamath.org/mpeuni/wif.html). I propose to move it to the main part for the following reasons: * it is a pretty natural operator * it is analogous

[Metamath] Re: New Gource visualization of set.mm

2019-10-05 Thread Benoit
Looks great ! Maybe moving the captions lower-left (instead of lower-center) would make both the captions and the graph more legible (the captions, because they would be left-aligned, and the graph, because it would be less obstructed by the captions). It's a bit strange that at around 0:01,

Re: [Metamath] Re: [set.mm] The conditional operator for propositions

2019-10-06 Thread Benoit
> > (Actually df-v is an exception; it should probably read { x | T. } and I > guess the use of x = x is a historical accident?) > This has been proposed in https://groups.google.com/d/msg/metamath/V3jmbWUd_mM/RAk2DEA3FQAJ, with explanations that I still stand by. With the new definition

Re: [Metamath] Re: New Gource visualization of set.mm

2019-10-06 Thread Benoit
Hi David, I agree with Alexander that the paragraph "Unlike the Gource... improvements" can be removed (and the older video it mentions can be removed too, if youtube allows that). Concerning the following paragraph, I would shorten it to something like: The initial "big bang" effect is due

[Metamath] Re: Merry Christmas from Richard Penner

2019-12-25 Thread Benoit
> > 0. Thanks to Benoit Jubin for applying the rubric at the top of > CONTRIBUTING.md which enhances the instructions in > https://github.com/metamath/set.mm/wiki/Getting-started-with-contributing > <https://www.google.com/url?q=https%3A%2F%2Fgithub.com%2Fmetamath%2Fset.m

Re: [Metamath] Full 'minimize' run on set.mm

2020-02-13 Thread Benoit
David: yes, ~bisymOLD and ~bi3antOLD should have both discouragement tags. I'm away from my main computer... can you add them ? Actually, most *OLD and *ALT should probably have both discouragement tags as well, it seems ? Thanks, Benoît On Thursday, February 13, 2020 at 9:13:39 AM UTC+1,

Re: [Metamath] Re: Formalizing IMO B2.1972

2020-03-04 Thread Benoit
> > I started my quest towards IMO 1972 B2 by formalizing a simple > induction problem (just for fun): `( N e. NN -> 3 || ( ( 4 ^ N ) + 5 ) I think ~ inductionexd (with the caveat below) is a nice instructive example, and could be moved to main, as the first theorem of the new subsection

Re: [Metamath] Re: Formalizing IMO B2.1972

2020-03-04 Thread Benoit
Stan: you're right about the need to prove this (if using explicit substitution): look for the utility theorems exchanging [. / ]. with other symbols (quantifiers, operations). As said by Jim and Thierry, who are more experienced in proof building, implicit substitution might be easier to

Re: [Metamath] Re: Formalizing IMO B2.1972

2020-02-28 Thread Benoit
> One question for which I'm looking guidance is on using quantifiers or not. That's a very important question, and I hope someone with more experience will be able to shed some insight. In particular, if one has a hypothesis, say, "E. x ph", then it is common to see in textbooks things like

[Metamath] Re: Formalizing IMO B2.1972

2020-02-27 Thread Benoit
Another proof I just found (sorry, it's not about the formalization): Let x be such that f(x) \neq 0 and let y \in \R. Set a = g(y). Set u_n = f(x + ny) for n \in \Z. It satisfies the linear recurrence relation u_{n+2} = 2a u_{n+1} - u_n. The characteristic relation is r^2 - 2ar + 1 = 0. The

Re: [Metamath] Re: Formalizing IMO B2.1972

2020-02-27 Thread Benoit
> > I have stumbled upon the supremum definition but it looks more intricate > to use than a manually defining it inline on the real line (unless you’re > referring to another definition of the least upper bound). That’s precisely > one of the open questions I have about how to go about

[Metamath] Categories as extensible structures

2020-01-29 Thread Benoit
Here is a question prompted by my remark in https://groups.google.com/d/msg/metamath/Nvh_ue-PSBM/Nj-XpBvBAAAJ "there is some gymnastic to do to put things in the right "slot", which looks painful..." I see in ~df-cat that if c is a category, then ( Base " c ) is actually the set of objects

Re: [Metamath] Categories as extensible structures

2020-01-30 Thread Benoit
Ok. I'm not insisting since I'm not fond of extensible structures anyway. But it is certainly not odd to make morphisms the underlying set of a category. The fact that an "arrows only" definition of a category is possible shows that it's that latter set which is more important. Also, it is

Re: [Metamath] Re: Philosophy and goals for set.mm

2020-02-01 Thread Benoit
On Saturday, February 1, 2020 at 3:37:57 AM UTC+1, Norman Megill wrote: > > On Friday, January 31, 2020 at 8:23:08 PM UTC-5, Benoit wrote: >> >> Regarding the possible introduction in the main part of semigroups and >> magmas: >> When I look at the page http://us2.m

Re: [Metamath] Re: Philosophy and goals for set.mm

2020-02-02 Thread Benoit
To answer FL's latest message: the first and foremost thing that Norm has done and still does for us is having created the Metamath language, continuously improving the Metamath C program (the "official implementation" of the Metamath language), and having begun and still being the main

Re: [Metamath] Re: Philosophy and goals for set.mm

2020-01-31 Thread Benoit
Regarding the possible introduction in the main part of semigroups and magmas: When I look at the page http://us2.metamath.org/mpeuni/df-mnd.html I feel a bit dizzy. The abundance of parentheses and conjunctions makes it hard to parse. Did you notice that the clause stating closedness is

Re: [Metamath] Full 'minimize' run on set.mm

2020-02-14 Thread Benoit
Thanks David. I looked at the corresponding MPE webpage (http://us2.metamath.org/mpeuni/mmtheorems21.html) and the following, and indeed aevALT ax16nfALT dral1ALT dveeq2ALT sbequ8ALT equsb3ALT should have the "(Proof modification is discouraged.)" tag. They already, and correctly, have the

[Metamath] Re: Analysis of full 'minimize' run on set.mm

2020-02-22 Thread Benoit
I think that the *ALT and *OLD theorems appearing in the list (and those I quoted earlier in this thread) can be given both discouragement tags. This will take care of most of "my" cases (and others). I can do it if Norm wants. As for the other minimizations of theorems of the form bj-* in

Re: [Metamath] Full 'minimize' run on set.mm

2020-02-15 Thread Benoit
> > Yes, ~hashssle is a specialization of ~hashss and could be replaced (and > removed afterwards). ~hashssle (and ~bj-abf), however, are in mathboxes. In > my opinion, the owners of the mathboxes should be responsible for cleaning > up such cases. But it would be great if a list of such cases

Re: [Metamath] Re: RFC: Mandatory definitions after constants

2020-02-13 Thread Benoit
On Thursday, February 13, 2020 at 5:46:36 PM UTC+1, Mario Carneiro wrote: > > That said, I think it would still be better to move all definitions needed > for df-prds before it. This is a downside of the "everything structure" > approach, but it does not displace too many definitions. We can

Re: [Metamath] Re: Difference between formal and classical math

2020-01-10 Thread Benoit
On Friday, January 10, 2020 at 1:52:20 AM UTC+1, Mario Carneiro wrote: > > we should have guarded the application to avoid seeing it in the first > place. > How would you do that ? (I gave some ideas some time ago on this group, but the drawbacks were deemed to outweigh the benefits.) Thanks,

[Metamath] Handling "undefined terms"

2020-01-11 Thread Benoit
As promised at the end of https://groups.google.com/d/topic/metamath/yzQnexbXv-8/discussion , I'm going to list a few ways I can think of to avoid "nonsensical", or "junk" theorems in set.mm. This is not a proposal to change anything in set.mm, at least for the moment. The only aim of this

Re: [Metamath] Re: Please move metamath 100 results into main body

2020-01-11 Thread Benoit
On Saturday, January 11, 2020 at 1:52:55 PM UTC+1, fl wrote: > > Someone suggested using Bourbaki as a guide for ordering the definitions > and theories related to structures. I think this is a good idea. > It is the longest and most comprehensive treatise on structures. > You probably refer to

Re: [Metamath] Re: Difference between formal and classical math

2020-01-11 Thread Benoit
Thanks. Yes, Mario's and David's suggestions are two possibilities I had in mind, with other, more strict ones, with the drawbacks alluded to above. I'll try to list them in a separate thread. Benoît -- You received this message because you are subscribed to the Google Groups "Metamath"

Re: [Metamath] Handling "undefined terms"

2020-01-12 Thread Benoit
On Saturday, January 11, 2020 at 10:44:31 PM UTC+1, Mario Carneiro wrote: > > qed::foo |- ( T. -> RH ) > I don't understand: it looks like you are using foo with the substitutions ph <- T. and THM <- RH, but in order to make the latter substitution, you need to prove that RH has type |- , which

Re: [Metamath] Proposal: Mark dummylink & idi with "(New usage is discouraged.)"

2020-01-12 Thread Benoit
This was proposed in PR #1105. There is an ensuing discussion. Benoît -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to metamath+unsubscr...@googlegroups.com. To

Re: [Metamath] Handling "undefined terms"

2020-01-12 Thread Benoit
unday, January 12, 2020 at 6:09:52 PM UTC-5, Norman Megill wrote: >> >> On Sunday, January 12, 2020 at 5:24:59 PM UTC-5, Benoit wrote: >>> >>> On Saturday, January 11, 2020 at 10:44:31 PM UTC+1, Mario Carneiro wrote: >>> >> >> ... >> >

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