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Directed graph

Published: 2014/12/01

Channel: jonmcire

Data structures: Properties of Graphs

Published: 2014/09/16

Channel: mycodeschool

136. Directed and Undirected Graph (Hindi)

Published: 2016/07/30

Channel: Geeky Shows

Detect Cycle in Directed Graph Algorithm

Published: 2016/01/16

Channel: Tushar Roy - Coding Made Simple

Dijkstras Algorithm Directed Graph Example

Published: 2015/06/21

Channel: Joe James

Detect Cycle in a Directed Graph | GeeksforGeeks

Published: 2017/01/12

Channel: GeeksforGeeks

Graph Theory -17 Adjacency Matrix of a Directed Connected Graph

Published: 2016/05/26

Channel: Bikki Mahato

Directed Depth First Search - Example 1

Published: 2014/11/05

Channel: Shawn Lupoli

Directed graphs for relations (Screencast 7.1.2)

Published: 2012/11/20

Channel: GVSUmath

8.2 Directed Graphs

Published: 2016/11/07

Channel: Bobby Lloyd

Discrete Mathematics : Digraphs and Relations

Published: 2013/02/01

Channel: Dragonfly Statistics

ADJACENCY MATRIX OF A DIGRAPH(GRAPH THEORY-3)

Published: 2014/08/06

Channel: OnlineTeacher

Graphs - Breadth First Search

Published: 2014/04/18

Channel: zooce

Graphs: Dijkstra's Algorithm

Published: 2008/04/02

Channel: distanceedjohn

GRAPHS AND DIGRAPHS(GRAPH THEORY-1)

Published: 2014/08/06

Channel: OnlineTeacher

How to D3 Force Directed Layout Graph

Published: 2016/06/30

Channel: Teslanomics by Ben Sullins

Breadth-First Search of a Directed Graph

Published: 2016/10/18

Channel: David Sturgill

Detect Cycle in a Directed graph using colors | GeeksforGeeks

Published: 2017/02/04

Channel: GeeksforGeeks

Directed Acyclic Graph (DAG) Single Source Shortest Paths with Example

Published: 2016/03/13

Channel: Algorithms with Attitude

Graphs-Directed Acyclic Graphs - Data Structures & Algorithms

Published: 2015/09/29

Channel: shashank misra

Directed Graphs - Reachability and Dominance

Published: 2014/06/24

Channel: TheTeachersBeehive

Directed weighted graph representation pt1

Published: 2016/06/09

Channel: Kyle Enzweiler

Force-Directed Graph VR | DevUp 2016-12-07

Published: 2016/12/07

Channel: Aesthetic Interactive

Website : Force-Directed graph drawing

Published: 2015/03/25

Channel: Michel Remise

Using custom visuals - The Force-Directed Graph

Published: 2015/11/18

Channel: Microsoft Power BI

Johnson's Algorithm - All simple cycles in directed graph

Published: 2015/11/23

Channel: Tushar Roy - Coding Made Simple

Graphs - Depth First Search

Published: 2014/04/07

Channel: zooce

Depth-first Search (DFS) on Graphs Part 1 - Algorithm

Published: 2014/03/19

Channel: Sesh Venugopal

Force Directed Graph - my experiment

Published: 2009/04/02

Channel: dbnull

Power BI Custom Visuals - Force-Directed Graph

Published: 2016/10/31

Channel: Pragmatic Works

Floyd's Algorithm - Directed Graph - step by step guide

Published: 2016/01/10

Channel: Yusuf Shakeel

Random Walk on Random Directed Graphs

Published: 2016/02/29

Channel: Simons Institute

Graphs Adjacency Lists and Matrices

Published: 2014/04/18

Channel: zooce

Force-Directed Graph VR | DevUp 2017-02-17

Published: 2017/04/06

Channel: Aesthetic Interactive

Topological Sort Graph Algorithm

Published: 2015/08/03

Channel: Tushar Roy - Coding Made Simple

Strongly Connected Components Kosaraju's Algorithm Graph Algorithm

Published: 2015/08/13

Channel: Tushar Roy - Coding Made Simple

Applications of Traversals - Cycle in Directed Graph

Published: 2017/07/03

Channel: GATE CS LECTURES BY GATE BOOK

Breadth-first Search (BFS) on Graphs Part 1 - Algorithm

Published: 2016/06/10

Channel: Sesh Venugopal

TRANSITIVE CLOSURE OF A DIRECTED GRAPH

Published: 2015/06/03

Channel: OnlineTeacher

Assign directions to edges so that the directed graph remains acyclic | GeeksforGeeks

Published: 2016/07/22

Channel: GeeksforGeeks

MTH109 CT2: Directed Graph Problem Solution

Published: 2013/05/04

Channel: Craig Storlie

Random Walks on Directed Graphs

Published: 2014/11/03

Channel: Simons Institute

BFS Directed - Example 1

Published: 2015/02/20

Channel: Shawn Lupoli

Dijkstra Directed Graph Part 1

Published: 2016/05/09

Channel: Jairaj Ramkissoon

Force-Directed Layout Tutorial « AllegroLayout | Cytoscape 3 App

Published: 2014/05/11

Channel: AllegroViva

Draw Graph Using force-directed graph drawing Algorithm

Published: 2013/12/23

Channel: ExpertProTutor

Applications of Traversals -Directed Graph Connected components

Published: 2017/07/03

Channel: GATE CS LECTURES BY GATE BOOK

Lecture - 29 DFS in Directed Graphs

Published: 2008/09/24

Channel: nptelhrd

Directed Graph Depth-First Search

Published: 2016/10/18

Channel: David Sturgill

Hololens Experiment: A force-directed graph

Published: 2016/06/21

Channel: Michael Peters

In mathematics, and more specifically in graph theory, a **directed graph** (or **digraph**) is a graph that is a set of vertices connected by edges, where the edges have a direction associated with them.

In formal terms, a directed graph is an ordered pair *G* = (*V*, *A*) where^{[1]}

*V*is a set whose elements are called*vertices*,*nodes*, or*points*;*A*is a set of ordered pairs of vertices, called*arrows*,*directed edges*(sometimes simply*edges*with the corresponding set named*E*instead of*A*),*directed arcs*, or*directed lines*.

It differs from an ordinary or undirected graph, in that the latter is defined in terms of unordered pairs of vertices, which are usually called *edges*, *arcs*, or *lines*.

The aforementioned definition does not allow a directed graph to have multiple arrows with same source and target nodes, but some authors consider a broader definition that allow directed graphs to have such multiple arrows (namely, they allow the arrows set to be a multiset). More specifically, these entities are addressed as **directed multigraphs** (or **multidigraphs**).

On the other hand, the aforementioned definition allows a directed graph to have loops (that is, arrows that connect nodes with themselves), but some authors consider a narrower definition that doesn't allow directed graphs to have loops.^{[2]} More specifically, directed graphs without loops are addressed as **simple directed graphs**, while directed graphs with loops are addressed as *loop-digraphs* (see section Types of directed graphs).

**Symmetric directed graphs**are directed graphs where all edges are bidirected (that is, for every arrow that belongs to the digraph, the corresponding inversed arrow also belongs to it).**Simple directed graphs**are directed graphs that have no loops (arrows that connect vertices to themselves) and no multiple arrows with same source and target nodes. As already introduced, in case of multiple arrows the entity is usually addressed as*directed multigraph*. Some authors describe digraphs with loops as*loop-digraphs*.^{[2]}**Complete directed graphs**are simple directed graphs where each pair of vertices is joined by a symmetric pair of directed arrows (it is equivalent to an undirected complete graph with the edges replaced by pairs of inverse arrows). It follows that a complete digraph is symmetric.**Oriented graphs**are directed graphs having no bidirected edges (i.e. at most one of (*x*,*y*) and (*y*,*x*) may be arrows of the graph). It follows that a directed graph is an oriented graph iff it hasn't any 2-cycle.^{[3]}**Tournaments**are oriented graphs obtained by choosing a direction for each edge in undirected complete graphs.**Directed acyclic graphs**(DAGs) are directed graphs with no directed cycles.*Multitrees*are DAGs in which no two directed paths from a single starting vertex meet back at the same ending vertex.*Oriented trees*or*polytrees*are DAGs formed by orienting the edges of undirected acyclic graphs.*Rooted trees*are oriented trees in which all edges of the underlying undirected tree are directed away from the roots.

**Weighted directed graphs**(also known as**directed networks**) are (simple) directed graphs with*weights*assigned to their arrows, similarly to weighted graphs (which are also known as undirected networks or weighted networks).^{[2]}**Flow networks**are weighted directed graphs where two nodes are distinguished, a*source*and a*sink*.

**Rooted directed graphs**(also known as**flow graphs**) are digraphs in which a vertex has been distinguished as the root.*Control flow graphs*are rooted digraphs used in computer science as a representation of the paths that might be traversed through a program during its execution.

**Signal-flow graphs**are directed graphs in which nodes represent system variables and branches (edges, arcs, or arrows) represent functional connections between pairs of nodes.**Flow graphs**are digraphs associated with a set of linear algebraic or differential equations.**State diagrams**are directed multigraphs that represent finite state machines.**Commutative diagrams**are digraphs used in category theory, where the vertices represent (mathematical) objects and the arrows represent morphisms, with the property that all directed paths with the same start and endpoints lead to the same result by composition.- In the theory of Lie groups, a
**quiver***Q*is a directed graph serving as the domain of, and thus characterizing the shape of, a*representation**V*defined as a functor, specifically an object of the functor category FinVct_{K}^{F(Q)}where*F*(*Q*) is the free category on*Q*consisting of paths in*Q*and FinVct_{K}is the category of finite-dimensional vector spaces over a field*K*. Representations of a quiver label its vertices with vector spaces and its edges (and hence paths) compatibly with linear transformations between them, and transform via natural transformations.

An arrow (*x*, *y*) is considered to be directed *from* *x* *to* *y*; *y* is called the *head* and *x* is called the *tail* of the arrow; *y* is said to be a *direct successor* of *x* and *x* is said to be a *direct predecessor* of *y*. If a path leads from *x* to *y*, then *y* is said to be a *successor* of *x* and *reachable* from *x*, and *x* is said to be a *predecessor* of *y*. The arrow (*y*, *x*) is called the *inverted arrow* of (*x*, *y*).

The adjacency matrix of a multidigraph with loops is the integer-valued matrix with rows and columns corresponding to the vertices, where a nondiagonal entry *a*_{ij} is the number of arrows from vertex *i* to vertex *j*, and the diagonal entry *a*_{ii} is the number of loops at vertex *i*. The adjacency matrix of a directed graph is unique up to identical permutation of rows and columns.

Another matrix representation for a directed graph is its incidence matrix.

See direction for more definitions.

For a vertex, the number of head ends adjacent to a vertex is called the *indegree* of the vertex and the number of tail ends adjacent to a vertex is its *outdegree* (called "branching factor" in trees).

Let *G* = (*V*, *A*) and *v*∈*V*. The indegree of *v* is denoted deg^{−}(*v*) and its outdegree is denoted deg^{+}(*v*).

A vertex with deg^{−}(*v*) = 0 is called a *source*, as it is the origin of each of its outcoming arrows. Similarly, a vertex with deg^{+}(*v*) = 0 is called a *sink*, since it is the end of each of its incoming arrows.

If a vertex is neither a *source* nor a *sink*, it is called an *internal*.

The *degree sum formula* states that, for a directed graph,

If for every vertex *v*∈*V*, deg^{+}(*v*) = deg^{−}(*v*), the graph is called a *balanced directed graph*.^{[4]}

The degree sequence of a directed graph is the list of its indegree and outdegree pairs; for the above example we have degree sequence ((2, 0), (2, 2), (0, 2), (1, 1)). The degree sequence is a directed graph invariant so isomorphic directed graphs have the same degree sequence. However, the degree sequence does not, in general, uniquely identify a directed graph; in some cases, non-isomorphic digraphs have the same degree sequence.

The directed graph realization problem is the problem of finding a directed graph with the degree sequence a given sequence of positive integer pairs. (Trailing pairs of zeros may be ignored since they are trivially realized by adding an appropriate number of isolated vertices to the directed graph.) A sequence which is the degree sequence of some directed graph, i.e. for which the directed graph realization problem has a solution, is called a directed graphic or directed graphical sequence. This problem can either be solved by the Kleitman–Wang algorithm or by the Fulkerson–Chen–Anstee theorem.

A directed graph is *weakly connected* (or just *connected*^{[5]}) if the undirected *underlying graph* obtained by replacing all directed edges of the graph with undirected edges is a connected graph. A directed graph is *strongly connected* or *strong* if it contains a directed path from *x* to *y* and a directed path from *y* to *x* for every pair of vertices {*x*, *y*}. The *strong components* are the maximal strongly connected subgraphs.

Wikimedia Commons has media related to .Directed graphs |

- Coates graph
- Flow chart
- Glossary of graph theory
- Graph theory
- Graph (abstract data type)
- Network theory
- Orientation
- Preorder
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- Vertical constraint graph

**^**Bang-Jensen & Gutin (2000). Diestel (2005), Section 1.10. Bondy & Murty (1976), Section 10.- ^
^{a}^{b}^{c}Chartrand, Gary (1977).*Introductory Graph Theory*. Courier Corporation. ISBN 9780486247755. **^**Diestel (2005), Section 1.10.**^**Satyanarayana, Bhavanari; Prasad, Kuncham Syam,*Discrete Mathematics and Graph Theory*, PHI Learning Pvt. Ltd., p. 460, ISBN 978-81-203-3842-5; Brualdi, Richard A. (2006),*Combinatorial Matrix Classes*, Encyclopedia of Mathematics and Its Applications,**108**, Cambridge University Press, p. 51, ISBN 978-0-521-86565-4.**^**Bang-Jensen & Gutin (2000) p. 19 in the 2007 edition; p. 20 in the 2nd edition (2009).

- Bang-Jensen, Jørgen; Gutin, Gregory (2000),
*directed graphs: Theory, Algorithms and Applications*, Springer, ISBN 1-85233-268-9

(the corrected 1st edition of 2007 is now freely available on the authors' site; the 2nd edition appeared in 2009 ISBN 1-84800-997-6). - Bondy, John Adrian; Murty, U. S. R. (1976),
*Graph Theory with Applications*, North-Holland, ISBN 0-444-19451-7, archived from the original on 2010-04-13. - Diestel, Reinhard (2005),
*Graph Theory*(3rd ed.), Springer, ISBN 3-540-26182-6 (the electronic 3rd edition is freely available on author's site). - Harary, Frank; Norman, Robert Z.; Cartwright, Dorwin (1965),
*Structural Models: An Introduction to the Theory of Directed Graphs*, New York: Wiley. - Number of directed graphs (or directed graphs) with n nodes from On-Line Encyclopedia of Integer Sequences

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