Questions tagged [topological-ordering]
The topological-ordering tag has no usage guidance.
22
questions
2
votes
0answers
18 views
How to mathematically prove that a topological ordering on a cyclic graph will topologically sort its Strongly Connected Components?
Let's have a standard topological ordering algorithm (from CLRS):
...
0
votes
1answer
31 views
What is the relation between Topological Sort and Strongly Connected Components?
Both the Topological Sorting algorithm and the algorithm to find Strongly Connected Components build a stack whose top is the last visited vertex.
I find difficult to find an explaination because ...
2
votes
1answer
187 views
Topological sort with minimum maximal distance in array
I have a DAG that admits many possible topological sorts. I want to construct one that has the minimum maximum distance between a node and its neighbours in an array storing the nodes in sorted order.
...
2
votes
1answer
164 views
Topological sort and finding longest path in DAG to solve a stacking boxes variation (no rotation)
Given n elements (boxes) I have to output the max number of boxes that can fit one into another. Each box has width (x), height (y) and depth (z). One box j can hold another box k if: ...
2
votes
1answer
39 views
Is doing BFS over transitive reduction of a directed acyclic graph equivalent to topological ordering of that graph?
I have a directed acyclic graph. Where each node is a task and each edge denotes a dependency.
I want a method to effectively parallelize these tasks. One way would be to topological sort them based ...
2
votes
0answers
46 views
Constrained/Optimal Topological Order to enhance/reduce the performance/memory usage of other algorithms
I originally posted this question here
Lets assume we have a highly connected directed acyclic graph (DAG, more edges then nodes). Since it is a DAG, we can retrieve a topological order of nodes to ...
1
vote
1answer
54 views
Prove the following claim on Hamilton Path?
I am trying to prove the following claim:
Given DAG graph, there is Hamilton path iff the following algorithm
returns true:
Do topologic sorting.
Move on the graph's vertices one by one (from low to ...
0
votes
1answer
66 views
DFS produces the correct Topologically ordered sequence
Prove that DFS produces the correct topologically ordered sequence.
I am having a hard time understanding the question itself. Should I prove the correctness of DFS? Should I use the pseudocode?
0
votes
2answers
22 views
Valid orderings for topological sort
I am reading Algorithms by Dasgupta et al and the graph section provides an example graph and mentions that there are 4 orderings with one of them being B, A, D, C, E, F.
Are the other 3?
B, A, D, C,...
2
votes
2answers
148 views
Ordering of operations in a DAG of git commits
Context: I'm looking for a better state resolution algorithm for https://github.com/MichaelMure/git-bug
Summary of the current algorithm and shortcomings
git-bug is a distributed bug-tracker that ...
2
votes
1answer
44 views
Modified topological sort
I recently asked a related question at the theoretical CS stack exchange, but I have modification to the problem that I think is a bit tougher. This seems like a better place anyways.
Let's define a &...
1
vote
0answers
28 views
Proof that "the last vertex in any postordering (in a DFS) of G lies in a source component of G"
From the book Algorithms (Jeff Erickson), there's a lemma that states:
The last vertex in any postordering of G lies in a source component
of G
My initial reaction to this was that the proof would ...
6
votes
5answers
333 views
How to edge-color a directed acyclic graph so that every path visits none or all edges of each color?
Given a directed acyclic graph $G$ and a start vertex $s$ and an end vertex $e$, consider a coloring of the edges valid if, for every path from $s$ to $e$ and every color $c$, either $c$ is never ...
1
vote
0answers
36 views
Optimally find one of the total orderings for a poset based on some metadata about the elements
Given a finite, partially ordered set with the following two properties:
Every element in the set has one of two types: "A" or "B". The type does not define the total ordering of the set and is ...
0
votes
1answer
179 views
Is topological sort of an original graph same as post-ordering dfs of its transpose graph
I have an intuition that topo-sort of an original graph
A -> B -> C
D -> B
topo-sort is [D, A, B, C] or [A, D, B, C]
If I transpose the graph
<...
1
vote
0answers
16 views
Shortest sequence of jobs, with dependencies, subject to capacity constraints
Suppose I have $n$ courses, some with some prerequisites, and I can take up to $k$ courses in a semester. I want to compute the least number of semesters needed to complete all courses, while ...
0
votes
1answer
541 views
Why do we do topological sorting to find shortest or longest path in weighted DAG?
I was wondering why do we need to do the topological sort before performing relaxing of edges.
Wouldn't it'd be better if we do :
if starting vertex is "s"
...
3
votes
1answer
317 views
Construct a DAG from given multiple topological orderings
I need to construct a DAG, from its given topological orderings (i.e. the graph $G$ created must have all the orderings given as its topological orderings). For simplicity, the vertices are labeled as ...
6
votes
1answer
132 views
Is there an algorithm to minimize working set during a topological traversal?
I have a dependency graph of tasks, which forms a DAG. I'm looking for an algorithm to calculate the optimal topological traverse to minimize the "working set". Specifically, I define the current ...
1
vote
1answer
1k views
Determine whether there exists a path in a directed acyclic graph that reaches all nodes without revisiting a node
For this I came up with a DFS recursion.
Do DFS from any node and keep doing it until all nodes are Exhausted. I.E. pick the next unvisited node once you cannot keep recursing.
The element with ...
3
votes
0answers
100 views
Order the vertices to maximize the weights of edges in the induced subgraph
I have a complete directed graph $G:=(V,E)$ with directed edge weights $c_{ij}$ for every distinct nodes $i$ and $j$.
Goal: Find the topological order such that the smallest edge weight of the ...
0
votes
1answer
37 views
Topological Ordering
I have learnt to solve topological ordering using $in-degree$ method where we have to take the vertices having in-degree $0$ at an instance and arrange them in that order.
For example consider ...
