ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Tue, 01 Oct 2013 16:55:26 +0200Posets O(P) Algorithm, how to?https://ask.sagemath.org/question/10586/posets-op-algorithm-how-to/Hi!
I an new here :). I am doing some work with Posets, and I want to create O(P) given a Poset P. The idea is to give a graphic representation. I want to use sage for this (it has the functions for it). But, The graphical representation is bad (It does not show the elements of the poset, just a number, it represents the structure though).
We (we are a team) implemented something in php (to have it online). Now we want to implement O(P) (We have how to construct P) so that we can see in each node the corresponding element. Can anyone tell me how to do this? or where I can find an algorithm or the source code in sage? What I want is (in sage):
P = Poset((divisors(12), attrcall("divides")), facade=True)
A = P.directed_subsets('up')
L = sorted(list(A))
PP = Poset(([Set(s) for s in L], attrcall("issubset")))
PP._hasse_diagram.plot()
(If there is a way to see the elements with PP._hasse_diagram.plot() will be appreciated.)
Where I can find the source code or (better I think) an algorithm to create O(P) in an efficient way? For example, how to calculate the antichains (if this helps) to create each element (each down-set) of O(P) and then how to create O(P)?ShariffTue, 01 Oct 2013 16:55:26 +0200https://ask.sagemath.org/question/10586/How to plot O(P) of a Poset P in sage?https://ask.sagemath.org/question/10571/how-to-plot-op-of-a-poset-p-in-sage/Hello,
I just installed sage. I want to use it to do some things with Posets for my Modern ALgebra Class. For example, I want to use it to compute and plot the O(P) of a poset P. (The Poset of the order ideals of P).
1- Where I can find examples of how to construct Posets? I know that in the references they are some examples, but is there some type of tutorial with Posets or pdf with examples?
2- How I can plot O(P)? I know that there is a method called P.directed_subsets('down') to compute the down sets of P. The problem is that this method returns a List... So I can't plot a hasse diagram of it... For example:
P = Poset((divisors(12), attrcall("divides")), facade=True)
A = P.directed_subsets('up')
sorted(list(A))
[[], [1, 2, 4, 3, 6, 12], [2, 4, 3, 6, 12], [2, 4, 6, 12], [3, 6, 12], [4, 3, 6, 12], [4, 6, 12], [4, 12], [6, 12], [12]]
3- I dont understand the order_ideals method. What are the parameters of this function??
Thanks!!
Note: As you see, I am very new here, some insight of how to work with sage is appreciated!ShariffFri, 27 Sep 2013 22:03:42 +0200https://ask.sagemath.org/question/10571/