Sage: Ticket #19191: LatticePoset: add is_planar()
https://trac.sagemath.org/ticket/19191
<p>
Add <code>is_planar()</code> to <code>LatticePoset</code>. See <a class="ext-link" href="http://www.sciencedirect.com/science/article/pii/0095895676900241"><span class="icon"></span>http://www.sciencedirect.com/science/article/pii/0095895676900241</a> for definition.
</p>
en-usSagehttps://trac.sagemath.org/chrome/site/logo_sagemath_trac.png
https://trac.sagemath.org/ticket/19191
Trac 1.1.6jmantysaloSat, 12 Sep 2015 04:45:55 GMTbranch set
https://trac.sagemath.org/ticket/19191#comment:1
https://trac.sagemath.org/ticket/19191#comment:1
<ul>
<li><strong>branch</strong>
set to <em>u/jmantysalo/latticeposet__add_is_planar__</em>
</li>
</ul>
TicketjmantysaloSat, 12 Sep 2015 04:48:11 GMTstatus changed; commit, dependencies set
https://trac.sagemath.org/ticket/19191#comment:2
https://trac.sagemath.org/ticket/19191#comment:2
<ul>
<li><strong>status</strong>
changed from <em>new</em> to <em>needs_review</em>
</li>
<li><strong>commit</strong>
set to <em>626fc056a36488adc942d37dd5a7a531828b9b48</em>
</li>
<li><strong>dependencies</strong>
set to <em>#19193</em>
</li>
</ul>
<p>
Ready for review, BUT please note the dependency: This will work when <a class="closed ticket" href="https://trac.sagemath.org/ticket/19193" title="defect: is_planar() fails with an immutable graph (closed: fixed)">#19193</a> has been fixed.
</p>
<hr />
<p>
New commits:
</p>
<table class="wiki">
<tr><td><a class="ext-link" href="http://git.sagemath.org/sage.git/commit/?id=626fc056a36488adc942d37dd5a7a531828b9b48"><span class="icon"></span>626fc05</a></td><td><code>Added is_planar() to lattices.</code>
</td></tr></table>
TicketncohenSun, 13 Sep 2015 10:47:55 GMT
https://trac.sagemath.org/ticket/19191#comment:3
https://trac.sagemath.org/ticket/19191#comment:3
<p>
You should work on a copy of the integer-labelled hasse diagram. Skip labels whenever you can.
</p>
TicketgitSun, 13 Sep 2015 12:55:43 GMTcommit changed
https://trac.sagemath.org/ticket/19191#comment:4
https://trac.sagemath.org/ticket/19191#comment:4
<ul>
<li><strong>commit</strong>
changed from <em>626fc056a36488adc942d37dd5a7a531828b9b48</em> to <em>c669ecbf2476518175f0719ba25e76cdc05f1521</em>
</li>
</ul>
<p>
Branch pushed to git repo; I updated commit sha1. New commits:
</p>
<table class="wiki">
<tr><td><a class="ext-link" href="http://git.sagemath.org/sage.git/commit/?id=c669ecbf2476518175f0719ba25e76cdc05f1521"><span class="icon"></span>c669ecb</a></td><td><code>Use directly the Hasse diagram.</code>
</td></tr></table>
TicketjmantysaloSun, 13 Sep 2015 12:57:57 GMT
https://trac.sagemath.org/ticket/19191#comment:5
https://trac.sagemath.org/ticket/19191#comment:5
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:3" title="Comment 3">ncohen</a>:
</p>
<blockquote class="citation">
<p>
You should work on a copy of the integer-labelled hasse diagram. Skip labels whenever you can.
</p>
</blockquote>
<p>
True. Corrected. Thanks!
</p>
<p>
I left this technically as needs_review, because this should be OK after <a class="closed ticket" href="https://trac.sagemath.org/ticket/19193" title="defect: is_planar() fails with an immutable graph (closed: fixed)">#19193</a>.
</p>
TicketjmantysaloFri, 18 Sep 2015 12:17:03 GMTcc set; dependencies deleted
https://trac.sagemath.org/ticket/19191#comment:6
https://trac.sagemath.org/ticket/19191#comment:6
<ul>
<li><strong>cc</strong>
<em>nthiery</em> added
</li>
<li><strong>dependencies</strong>
<em>#19193</em> deleted
</li>
</ul>
<p>
An easy review. Let's try Nicolas as a random victim for possible reviewer.
</p>
TicketncohenFri, 18 Sep 2015 12:19:47 GMT
https://trac.sagemath.org/ticket/19191#comment:7
https://trac.sagemath.org/ticket/19191#comment:7
<p>
This sentence seems in contradiction with the code, which adds a <code>(0,n-1)</code> edge
</p>
<pre class="wiki">+ A lattice is planar if it's Hasse diagram can be drawn on a
+ plane without crossing lines.
</pre><p>
Nathann
</p>
TicketjmantysaloFri, 18 Sep 2015 12:21:41 GMT
https://trac.sagemath.org/ticket/19191#comment:8
https://trac.sagemath.org/ticket/19191#comment:8
<p>
Next paragraph explains what is the meaning of Hasse diagram (i.e. have a right direction). But OK, I'll think better phrasing.
</p>
TicketncohenFri, 18 Sep 2015 12:26:52 GMT
https://trac.sagemath.org/ticket/19191#comment:9
https://trac.sagemath.org/ticket/19191#comment:9
<p>
<a class="ext-link" href="http://www.sciencedirect.com/science/article/pii/009589567790048X"><span class="icon"></span>http://www.sciencedirect.com/science/article/pii/009589567790048X</a>
</p>
<p>
The abstract of this paper is rather clear on what a planar poset is supposed to be.
</p>
<p>
Nathann
</p>
TicketjmantysaloFri, 18 Sep 2015 12:44:30 GMT
https://trac.sagemath.org/ticket/19191#comment:10
https://trac.sagemath.org/ticket/19191#comment:10
<p>
"A partially ordered set (poset) is planar if it has a planar Hasse diagram."? Quite short...
</p>
<p>
How about
</p>
<p>
"A lattice is planar if it has a planar Hasse diagram --- that is, it can be drawn to a plane without crossing lines and every covering relationg directed upwards."?
</p>
<p>
And yes, this function could be defined on a general poset. But then it is NP-complete.
</p>
TicketncohenFri, 18 Sep 2015 12:51:06 GMT
https://trac.sagemath.org/ticket/19191#comment:11
https://trac.sagemath.org/ticket/19191#comment:11
<p>
Sorry Jori, I do not follow you: the paper whose link I posted in a previous comment says that a poset is planar if its hasse diagram is planar. I see no mention of an additional edge (that you add in your code), and it is clearly polynomial at all times.
</p>
TicketjmantysaloFri, 18 Sep 2015 13:00:20 GMT
https://trac.sagemath.org/ticket/19191#comment:12
https://trac.sagemath.org/ticket/19191#comment:12
<p>
This is about planarity of lattices, not posets in general.
</p>
<p>
See for example <a class="ext-link" href="http://www.sciencedirect.com/science/article/pii/0095895676900241"><span class="icon"></span>http://www.sciencedirect.com/science/article/pii/0095895676900241</a> or <a class="ext-link" href="http://www.math.louisville.edu/Cumberland/slides/52%20-%20Trotter.pdf"><span class="icon"></span>http://www.math.louisville.edu/Cumberland/slides/52%20-%20Trotter.pdf</a> slide 12.
</p>
TicketncohenFri, 18 Sep 2015 13:10:35 GMT
https://trac.sagemath.org/ticket/19191#comment:13
https://trac.sagemath.org/ticket/19191#comment:13
<blockquote class="citation">
<p>
This is about planarity of lattices, not posets in general.
</p>
</blockquote>
<p>
The paper I sent you previously says that a *Poset* is planar if its hasse diagram is planar.
</p>
<p>
The first paragraph (not the abstract) in the first paper that you mentionned says that the definition is (naturally) the same for posets, i.e. that they are planar whenever their hasse diagram is planar.
</p>
<p>
What the first paper claims in its title is that you can *chose* to add the <code>(0,n-1)</code> edge without changing the property.
</p>
<p>
What the slideshow says in its 12th page looks contradictory with the two papers above. If you can find the paper it quotes, perhaps that will clarify it.
</p>
<p>
Nathann
</p>
TicketjmantysaloSat, 19 Sep 2015 08:42:40 GMT
https://trac.sagemath.org/ticket/19191#comment:14
https://trac.sagemath.org/ticket/19191#comment:14
<p>
There seems to be same concept in plain graph theory: <em>upward planar</em> DAG. See <a class="ext-link" href="https://en.wikipedia.org/wiki/Upward_planar_drawing"><span class="icon"></span>https://en.wikipedia.org/wiki/Upward_planar_drawing</a>
</p>
<p>
The abstract of first paper I mentioned starts with "It is shown that a finite lattice is planar if and only if the (undirected) graph obtained from its (Hasse) diagram by adding an edge between its least and greatest elements is a planar graph." And this makes no sense if planarity of lattices would equal to planarity of graphs.
</p>
<p>
The question is about meaning of Hasse diagram. Should we say that it is a special type of DAG, or that it is a DAG drawn with a limitation? I think that writers think about latter.
</p>
<p>
But of course 1) this must be made very clear in the documentation, and 2) it might have interesting question in it own to look properties of posets with planar covering relations graph.
</p>
TicketncohenSat, 19 Sep 2015 08:56:26 GMT
https://trac.sagemath.org/ticket/19191#comment:15
https://trac.sagemath.org/ticket/19191#comment:15
<blockquote class="citation">
<p>
The abstract of first paper I mentioned starts with "It is shown that a finite lattice is planar if and only if the (undirected) graph obtained from its (Hasse) diagram by adding an edge between its least and greatest elements is a planar graph." And this makes no sense if planarity of lattices would equal to planarity of graphs.
</p>
</blockquote>
<p>
It *does* make sense. It means that if a lattice is planar, then there is a drawing of it in which the top and bottom elements appear in the same face.
</p>
<blockquote class="citation">
<p>
The question is about meaning of Hasse diagram.
</p>
</blockquote>
<p>
As a reviewer, I just want to make sure that what the user will understand is what actually happens.
</p>
<p>
Nathann
</p>
TicketjmantysaloSat, 19 Sep 2015 09:44:05 GMT
https://trac.sagemath.org/ticket/19191#comment:16
https://trac.sagemath.org/ticket/19191#comment:16
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:15" title="Comment 15">ncohen</a>:
</p>
<blockquote class="citation">
<p>
As a reviewer, I just want to make sure that what the user will understand is what actually happens.
</p>
</blockquote>
<p>
How about
</p>
<p>
"A lattice is planar if it's Hasse diagram has an upward planar drawing. In other words, planar lattice can be drawn without crossing lines and every covering relation directed upwards."
</p>
<p>
?
</p>
TicketncohenSat, 19 Sep 2015 10:21:34 GMT
https://trac.sagemath.org/ticket/19191#comment:17
https://trac.sagemath.org/ticket/19191#comment:17
<p>
Jori,
</p>
<p>
Up to now, in all papers that I have seen, a Poset is defined to be planar when its hasse diagram is planar. Have you even found one paper that defines it differently?
</p>
<p>
If there is to be a <code>Lattice.is_planar</code> or a <code>Poset.is_planar</code>, I expect it to be <code>self._hasse_diagram.is_planar()</code>, and nothing else. Even the paper that mentions this additional edge between 0 and n-1 uses *this* definition (without the additional edge) and apparently proves that you can add this edge without changing the property.
</p>
<p>
The least I can say is that I *know* that some people would be entitled to believe that <code>Lattice.is_planar</code> does not add any edge, even without reading the documentation (did you ever read the documentation of <code>is_even</code> ?). And those must not be mislead.
</p>
<p>
If you want to implement another definition, it will have to be under another name.
</p>
<p>
Nathann
</p>
TicketjmantysaloSat, 19 Sep 2015 10:38:16 GMT
https://trac.sagemath.org/ticket/19191#comment:18
https://trac.sagemath.org/ticket/19191#comment:18
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:17" title="Comment 17">ncohen</a>:
</p>
<blockquote class="citation">
<p>
Even the paper that mentions this additional edge between 0 and n-1 uses *this* definition (without the additional edge) and apparently proves that you can add this edge without changing the property.
</p>
</blockquote>
<p>
No. Hasse diagram for <code>BooleanLattice(3)</code> is planar, but it has no upward planar drawing.
</p>
<blockquote class="citation">
<p>
If you want to implement another definition, it will have to be under another name.
</p>
</blockquote>
<p>
That's OK.
</p>
TicketgitMon, 21 Sep 2015 08:46:39 GMTcommit changed
https://trac.sagemath.org/ticket/19191#comment:19
https://trac.sagemath.org/ticket/19191#comment:19
<ul>
<li><strong>commit</strong>
changed from <em>c669ecbf2476518175f0719ba25e76cdc05f1521</em> to <em>da6a1f9536ac362eef45f565515c752afdf9c84f</em>
</li>
</ul>
<p>
Branch pushed to git repo; I updated commit sha1. New commits:
</p>
<table class="wiki">
<tr><td><a class="ext-link" href="http://git.sagemath.org/sage.git/commit/?id=da6a1f9536ac362eef45f565515c752afdf9c84f"><span class="icon"></span>da6a1f9</a></td><td><code>planar -> upward_planar.</code>
</td></tr></table>
TicketjmantysaloMon, 21 Sep 2015 08:57:45 GMTstatus changed; dependencies set
https://trac.sagemath.org/ticket/19191#comment:20
https://trac.sagemath.org/ticket/19191#comment:20
<ul>
<li><strong>status</strong>
changed from <em>needs_review</em> to <em>needs_info</em>
</li>
<li><strong>dependencies</strong>
set to <em>#19193</em>
</li>
</ul>
<p>
I committed a version with new name for the function.
</p>
<p>
But still, I do not understand. The term <em>planar lattice</em> is used by D. Kelly and I. Rival in Canadian Journal of Mathematics, june 1975. And it uses the definition I suggested at start. Also
<a class="ext-link" href="http://www.math.uh.edu/~hjm/1973_Lattice/p00512-p00518.pdf"><span class="icon"></span>http://www.math.uh.edu/~hjm/1973_Lattice/p00512-p00518.pdf</a> etc. uses this definition.
</p>
TicketncohenMon, 21 Sep 2015 09:08:14 GMT
https://trac.sagemath.org/ticket/19191#comment:21
https://trac.sagemath.org/ticket/19191#comment:21
<blockquote class="citation">
<p>
Also
<a class="ext-link" href="http://www.math.uh.edu/~hjm/1973_Lattice/p00512-p00518.pdf"><span class="icon"></span>http://www.math.uh.edu/~hjm/1973_Lattice/p00512-p00518.pdf</a> etc. uses this definition.
</p>
</blockquote>
<p>
At the bottom of page 1 in this paper I read "P is planar if it has a planar diagram", where "diagram" is defined, just above, to be equal to the hasse diagram.
</p>
<p>
Nathann
</p>
TicketjmantysaloMon, 21 Sep 2015 09:12:45 GMT
https://trac.sagemath.org/ticket/19191#comment:22
https://trac.sagemath.org/ticket/19191#comment:22
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:21" title="Comment 21">ncohen</a>:
</p>
<blockquote class="citation">
<blockquote class="citation">
<p>
Also
<a class="ext-link" href="http://www.math.uh.edu/~hjm/1973_Lattice/p00512-p00518.pdf"><span class="icon"></span>http://www.math.uh.edu/~hjm/1973_Lattice/p00512-p00518.pdf</a> etc. uses this definition.
</p>
</blockquote>
</blockquote>
<blockquote class="citation">
<p>
At the bottom of page 1 in this paper I read "P is planar if it has a planar diagram", where "diagram" is defined, just above, to be equal to the hasse diagram.
</p>
</blockquote>
<p>
"A diagram of P is a set of n points in the (x, y)-plane - - together with certain arcs between these points such that: a) If p_i covers p_j then y_i > y_j - -".
</p>
TicketncohenMon, 21 Sep 2015 09:16:27 GMT
https://trac.sagemath.org/ticket/19191#comment:23
https://trac.sagemath.org/ticket/19191#comment:23
<p>
Oh true. Coordinates. I had not noticed.
</p>
TicketncohenMon, 21 Sep 2015 09:23:25 GMT
https://trac.sagemath.org/ticket/19191#comment:24
https://trac.sagemath.org/ticket/19191#comment:24
<p>
I'm trying to find some recent publication in which I can check this terminology. It seems indeed that those guys could say that "the diagram is planar" and talk about this kind of embedding without saying it, but it sounds so absurdly misleading that I want to see it written in a paper written after I was born.
</p>
TicketncohenMon, 21 Sep 2015 09:43:06 GMT
https://trac.sagemath.org/ticket/19191#comment:25
https://trac.sagemath.org/ticket/19191#comment:25
<p>
Okay. You are right. This guy cites the same definition that you cite:
</p>
<p>
<a class="ext-link" href="http://mathoverflow.net/questions/198116/is-a-distributive-lattice-planar-iff-it-admits-no-b3-sublattice"><span class="icon"></span>http://mathoverflow.net/questions/198116/is-a-distributive-lattice-planar-iff-it-admits-no-b3-sublattice</a>
</p>
<p>
And, more importantly, this book [1] on page 93 (bottom). Or this dissertation [2] page 23.
</p>
<p>
So you were right from the beginning. And I still can't believe how on earth they thought wise to have two such definitions coexist when they are so close to each other. We end up with results like "there are posets whose hasse diagram is not planar, though the hasse diagram (as a graph) is planar".
</p>
<p>
Okay. So what do we do:
</p>
<p>
I obviously prefer it to be named "is_upward_planar", but that just says that I would prefer the standard poset terminology to be "is upward planar". Truth it that people working on posets expect it to be written "is_planar", so that's probably how it should be named.
</p>
<p>
Sorry for the loss of time. I guess I just needed some recent publications which did what your 72 paper does, i.e. say explicitly that planarity is not graph planarity.
</p>
<p>
I will now take your branch and work a bit on the documentation, just to make sure that people like me would not make the mistake if they read it. If they just read the function's name, well, they are lost.
</p>
<p>
Nathann
</p>
<p>
[1] <a class="ext-link" href="http://www.springer.com/us/book/9783319064123"><span class="icon"></span>http://www.springer.com/us/book/9783319064123</a>
[2] <a class="ext-link" href="https://tu-dresden.de/Members/christian.zschalig/dateien/dissertation_zschalig"><span class="icon"></span>https://tu-dresden.de/Members/christian.zschalig/dateien/dissertation_zschalig</a>
</p>
TicketjmantysaloMon, 21 Sep 2015 09:54:57 GMT
https://trac.sagemath.org/ticket/19191#comment:26
https://trac.sagemath.org/ticket/19191#comment:26
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:25" title="Comment 25">ncohen</a>:
</p>
<blockquote class="citation">
<p>
So you were right from the beginning. And I still can't believe how on earth they thought wise to have two such definitions coexist when they are so close to each other. - -
</p>
</blockquote>
<p>
Well, mathematicians do not always behave logically. <code>:=)</code>.
</p>
<p>
1) Is it technically possible to give positive review to a ticket like this, as this depends on closed ticket not yet at newewst beta? 2) This obviously needs clarification in documentation. But <code>NOTE</code> or even <code>WARNING</code>? It would say that <code>NOTE</code> is enought. 3) Is there easy way to undo last commit on ticket? Not that it would be that big thing in this specific case do by hand.
</p>
TicketncohenMon, 21 Sep 2015 10:01:48 GMT
https://trac.sagemath.org/ticket/19191#comment:27
https://trac.sagemath.org/ticket/19191#comment:27
<blockquote class="citation">
<p>
Well, mathematicians do not always behave logically. <code>:=)</code>.
</p>
</blockquote>
<p>
<code>-_-</code>
</p>
<blockquote class="citation">
<p>
1) Is it technically possible to give positive review to a ticket like this, as this depends on closed ticket not yet at newewst beta?
</p>
</blockquote>
<p>
The only thing that we must preserve is Volker's own happiness. It does not matter what you and I have on our hard drive: when a ticket is closed, it means that Volker's latest release contains the ticket. So you can assume that it is already applied.
</p>
<blockquote class="citation">
<p>
2) This obviously needs clarification in documentation. But <code>NOTE</code> or even <code>WARNING</code>? It would say that <code>NOTE</code> is enought.
</p>
</blockquote>
<p>
I agree. I only have a note in the version I am working on.
</p>
<blockquote class="citation">
<p>
3) Is there easy way to undo last commit on ticket?
</p>
</blockquote>
<p>
Yeah yeah. Look at 'git rebase -i', I use this all the time (look for 'squashing'). But don't worry about this, I am working on the branch and will push it shortly.
</p>
<p>
I still hesitate over this <code>is_planar</code> and <code>is_upward_planar</code>. If you really think that the first is better then let's do this, but if you believe that anybody who looks for <code>is_planar</code> would also think of trying <code>is_upward_planar</code> then the second is obviously safer. Tell me how you want it done, and I will update the branch accordingly.
</p>
<p>
Nathann
</p>
TicketjmantysaloMon, 21 Sep 2015 11:13:25 GMT
https://trac.sagemath.org/ticket/19191#comment:28
https://trac.sagemath.org/ticket/19191#comment:28
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:27" title="Comment 27">ncohen</a>:
</p>
<blockquote class="citation">
<p>
I still hesitate over this <code>is_planar</code> and <code>is_upward_planar</code>. If you really think that the first is better then let's do this, but if you believe that anybody who looks for <code>is_planar</code> would also think of trying <code>is_upward_planar</code> then the second is obviously safer. Tell me how you want it done, and I will update the branch accordingly.
</p>
</blockquote>
<p>
Googling "upward planar lattice" seems to found nothing. I guess it is good reason to have <code>is_planar()</code>, as it seems to be only used term.
</p>
<p>
(In the future we should not have problems like this. Just wait until <a class="wiki" href="https://trac.sagemath.org/wiki/SageMath">SageMath</a> is The Software and all questions about "what is exact definition of...?" will be answered "Sage defines...". <code>;=)</code>)
</p>
TicketncohenMon, 21 Sep 2015 11:18:30 GMT
https://trac.sagemath.org/ticket/19191#comment:29
https://trac.sagemath.org/ticket/19191#comment:29
<blockquote class="citation">
<p>
Googling "upward planar lattice" seems to found nothing. I guess it is good reason to have <code>is_planar()</code>, as it seems to be only used term.
</p>
</blockquote>
<p>
Okay, done at u/ncohen/19191. Note that I rewrote history.
</p>
<blockquote class="citation">
<p>
(In the future we should not have problems like this. Just wait until SageMath is The Software and all questions about "what is exact definition of...?" will be answered "Sage defines...". <code>;=)</code>)
</p>
</blockquote>
<p>
Yeah. Well if that's the case then I will regret even more this <code>Poset.is_planar</code>. At least I will have this trac tickets to use for my own defense <code>:-P</code>
</p>
<p>
Nathann
</p>
TicketjmantysaloMon, 21 Sep 2015 11:24:03 GMT
https://trac.sagemath.org/ticket/19191#comment:30
https://trac.sagemath.org/ticket/19191#comment:30
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:29" title="Comment 29">ncohen</a>:
</p>
<blockquote class="citation">
<p>
Okay, done at u/ncohen/19191. Note that I rewrote history.
</p>
</blockquote>
<p>
Seems good.
</p>
<p>
Remove dependency, as it is now handled differently. This will clash with <a class="closed ticket" href="https://trac.sagemath.org/ticket/19123" title="enhancement: LatticePoset: add is_vertically_decomposable (closed: fixed)">#19123</a>, but I can rebase it later.
</p>
TicketncohenMon, 21 Sep 2015 11:25:25 GMTstatus changed; reviewer set
https://trac.sagemath.org/ticket/19191#comment:31
https://trac.sagemath.org/ticket/19191#comment:31
<ul>
<li><strong>status</strong>
changed from <em>needs_info</em> to <em>needs_review</em>
</li>
<li><strong>reviewer</strong>
set to <em>Nathann Cohen</em>
</li>
</ul>
<blockquote class="citation">
<p>
Seems good.
</p>
</blockquote>
<p>
Then if you agree with it you can change the branch's name on this ticket, and set it to <code>positive_review</code> for inclusion.
</p>
<p>
Nathann
</p>
TicketjmantysaloMon, 21 Sep 2015 12:36:26 GMTreviewer, author, branch, commit changed; dependencies deleted
https://trac.sagemath.org/ticket/19191#comment:32
https://trac.sagemath.org/ticket/19191#comment:32
<ul>
<li><strong>reviewer</strong>
changed from <em>Nathann Cohen</em> to <em>Jori Mäntysalo, Nathann Cohen</em>
</li>
<li><strong>dependencies</strong>
<em>#19193</em> deleted
</li>
<li><strong>author</strong>
changed from <em>Jori Mäntysalo</em> to <em>Nathann Cohen, Jori Mäntysalo</em>
</li>
<li><strong>branch</strong>
changed from <em>u/jmantysalo/latticeposet__add_is_planar__</em> to <em>u/ncohen/19191</em>
</li>
<li><strong>commit</strong>
changed from <em>da6a1f9536ac362eef45f565515c752afdf9c84f</em> to <em>52a657ffca7acde0f622daffdbf0c066ea60887c</em>
</li>
</ul>
<p>
Going to compile to be sure.
</p>
<hr />
<p>
New commits:
</p>
<table class="wiki">
<tr><td><a class="ext-link" href="http://git.sagemath.org/sage.git/commit/?id=34529353f524802681f26009e7049f8f00ac7f0e"><span class="icon"></span>3452935</a></td><td><code>Added is_upward_planar() to lattices.</code>
</td></tr><tr><td><a class="ext-link" href="http://git.sagemath.org/sage.git/commit/?id=52a657ffca7acde0f622daffdbf0c066ea60887c"><span class="icon"></span>52a657f</a></td><td><code>trac #19191: Additional documentation</code>
</td></tr></table>
TicketjmantysaloMon, 21 Sep 2015 13:00:37 GMTstatus, description changed; dependencies set
https://trac.sagemath.org/ticket/19191#comment:33
https://trac.sagemath.org/ticket/19191#comment:33
<ul>
<li><strong>status</strong>
changed from <em>needs_review</em> to <em>positive_review</em>
</li>
<li><strong>dependencies</strong>
set to <em>#19193</em>
</li>
<li><strong>description</strong>
modified (<a href="/ticket/19191?action=diff&version=33">diff</a>)
</li>
</ul>
<p>
Duh, an example still depends on <a class="closed ticket" href="https://trac.sagemath.org/ticket/19193" title="defect: is_planar() fails with an immutable graph (closed: fixed)">#19193</a>. Added that. Now this seems to ready to go.
</p>
TicketnthieryMon, 21 Sep 2015 20:32:35 GMT
https://trac.sagemath.org/ticket/19191#comment:34
https://trac.sagemath.org/ticket/19191#comment:34
<p>
Replying to <a class="ticket" href="https://trac.sagemath.org/ticket/19191#comment:27" title="Comment 27">ncohen</a>:
</p>
<blockquote class="citation">
<p>
I still hesitate over this <code>is_planar</code> and <code>is_upward_planar</code>.
</p>
</blockquote>
<p>
For whatever it's worth (and it's late in the review process), I am
also hesitant. In papers it is often less of an issue to use short
names as the context helps removing ambiguities. So if someone comes
up with a good explicit <code>is_xxx_planar</code> suggestion (I don't have one),
that looks appealing. But that's just my 2cents; please proceed as you
see fit.
</p>
<p>
Cheers,
</p>
<blockquote>
<p>
Nicolas
</p>
</blockquote>
TicketvbraunTue, 22 Sep 2015 14:49:11 GMTstatus, branch changed; resolution set
https://trac.sagemath.org/ticket/19191#comment:35
https://trac.sagemath.org/ticket/19191#comment:35
<ul>
<li><strong>status</strong>
changed from <em>positive_review</em> to <em>closed</em>
</li>
<li><strong>resolution</strong>
set to <em>fixed</em>
</li>
<li><strong>branch</strong>
changed from <em>u/ncohen/19191</em> to <em>52a657ffca7acde0f622daffdbf0c066ea60887c</em>
</li>
</ul>
Ticket