re-org

Project.toml

@@ -9,6 +9,7 @@ Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
 HiGHS = "87dc4568-4c63-4d18-b0c0-bb2238e4078b"
 JuMP = "4076af6c-e467-56ae-b986-b466b2749572"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]

README.md

@@ -360,7 +360,11 @@ as do elements `n+1` through `2n`. The only relations are of the form `j < k` wh
 and `k = n+i` where `1 ≤ i ≤ n` and `i ≠ j`. This is a smallest-size poset of dimension `n`.
 * `chevron()` creates a poset with `6` elements that has dimension equal to `3`. It is 
 different from `standard_example(3)`. 
-* `semiorder(xs)` creates a semiorder. Here `xs` is a list of `n` real numbers. The result is a poset with `n` elements in which `i<j` when `x[i] ≤ x[j] - 1`. More generally, use `semiorder(xs,t)` in which case `i<j` when `x[i] ≤ x[j] - t`. Setting `t=0` gives a total order (if the values in `xs` are distinct). If `t` is negative, errors may be thrown. 
+* `random_linear_order(n)`: Create a linear order in which the numbers `1` through `n` appear in 
+random order.
+* `random_poset(n,d=2)`: Create a random `d`-dimensional poset by intersecting `d` random linear orders,
+each with `n` elements. 
+
 
 
 ## Graphs

extras/README.md

@@ -15,17 +15,18 @@ is a factor of the `b`-divisor.
 * `subsets_poset(n)`: Create a poset (isomorphic to) the $2^d$ subsets of a `d`-element set
 ordered by inclusion. 
 
-## `random_posets.jl`
-
-Functions provided:
-* `random_linear_order(n)`: Create a linear order in which the numbers `1` through `n` appear in 
-random order.
-
-* `random_poset(n,d=2)`: Create a random `d`-dimensional poset by intersecting `d` random linear orders,
-each with `n` elements. 
 
 ## `pplot.jl`
 
 Function provided:
 * `pplot(p)`: draw a picture of (the cover digraph of) `p`. An edge `v → w` means 
-`v < w` and `w` covers `v`. Use `pplot(p, nodelable=1:nv(p))` to have the nodes labeled.
+`v < w` and `w` covers `v`. Use `pplot(p, nodelable=1:nv(p))` to have the nodes labeled.
+
+
+## `interval_orders.jl`
+
+* `semiorder(xs)` creates a semiorder. Here `xs` is a list of `n` real numbers. 
+The result is a poset with `n` elements in which `i<j` when `x[i] ≤ x[j] - 1`. 
+More generally, use `semiorder(xs,t)` in which case `i<j` when `x[i] ≤ x[j] - t`. 
+Setting `t=0` gives a total order (if the values in `xs` are distinct). 
+If `t` is negative, errors may be thrown. 

extras/divisors.jl

@@ -49,3 +49,5 @@ function subsets_poset(d::Integer)
     n = prod(primes(d))  # product of first d primes
     return divisor_poset(n)
 end
+
+nothing

extras/interval-orders.jl

@@ -0,0 +1,22 @@
+using Posets, Graphs, ClosedIntervals
+
+"""
+    semiorder(values::Vector{T}, thresh=1) where {T<:Real}
+
+Create a semi-order from a list of numbers. In this poset we have `a<b` 
+exactly when `values[a] ≤ values[b] - thresh`.
+"""
+function semiorder(values::Vector{T}, thresh=1) where {T<:Real}
+    n = length(values)
+    g = DiGraph(n)
+    for a in 1:n
+        for b in 1:n
+            if values[a] <= values[b] - thresh
+                add_edge!(g, a, b)
+            end
+        end
+    end
+    return Poset(g)
+end
+
+nothing

extras/pplot.jl

@@ -13,3 +13,5 @@ function pplot(p::Poset; args...)
     g = cover_digraph(p)
     return gplot(g; args...)
 end
+
+nothing

src/Posets.jl

@@ -5,6 +5,8 @@ module Posets
 
 using Graphs
 using LinearAlgebra
+using Random
+
 using ChooseOptimizer
 using JuMP
 using HiGHS
@@ -63,6 +65,8 @@ export Poset,
     mobius_matrix,
     nr,
     nv,
+    random_linear_order,
+    random_poset,
     realizer,
     relations,
     rem_vertex!,
@@ -146,5 +150,6 @@ include("connection.jl")
 include("height-width.jl")
 include("realizer.jl")
 include("iso.jl")
+include("random-posets.jl")
 
 end # module Posets

extras/random_posets.jl → src/random-posets.jl

@@ -1,7 +1,3 @@
-using Posets
-using Graphs
-using Random
-
 """
     random_linear_order(n::Integer)
 

src/standard.jl

@@ -77,22 +77,3 @@ function chevron()
 
     return p
 end
-
-"""
-    semiorder(values::Vector{T}, thresh=1) where {T<:Real}
-
-Create a semi-order from a list of numbers. In this poset we have `a<b` 
-exactly when `values[a] ≤ values[b] - thresh`.
-"""
-function semiorder(values::Vector{T}, thresh=1) where {T<:Real}
-    n = length(values)
-    g = DiGraph(n)
-    for a in 1:n
-        for b in 1:n
-            if values[a] <= values[b] - thresh
-                add_edge!(g, a, b)
-            end
-        end
-    end
-    return Poset(g)
-end