**A digraph or directed graph is a pair G = (V, A) where V is a finite set of vertices and A ⊆ V × V is a multiset of ordered pairs of vertices, called arcs. A pair occurring more than once in A is called a multiple arc. An arc from u ∈ V to v ∈ V is denoted by (u, v).**

Similarly, What is DAG explain briefly? In computer science and mathematics, a directed acyclic graph (DAG) is **a graph that is directed and without cycles connecting the other edges**. This means that it is impossible to traverse the entire graph starting at one edge. The edges of the directed graph only go one way.

Then, What is a directed graph?

A directed graph, also called a digraph, is **a graph in which the edges have a direction**. This is usually indicated with an arrow on the edge; more formally, if v and w are vertices, an edge is an unordered pair {v,w}, while a directed edge, called an arc, is an ordered pair (v,w) or (w,v).

And How do you know if a graph is directed? **Directed graphs have edges with direction**. The edges indicate a one-way relationship, in that each edge can only be traversed in a single direction. This figure shows a simple directed graph with three nodes and two edges.

Is directed graph a simple graph? Some authors describe digraphs with loops as loop-digraphs. **Complete directed graphs are simple directed graphs** where each pair of vertices is joined by a symmetric pair of directed arcs (it is equivalent to an undirected complete graph with the edges replaced by pairs of inverse arcs).

**What is DAG and lineage graph?**

**Lineage graph deals with RDDs so it is applicable up-till transformations , Whereas, DAG shows the different stages of a spark job**. it shows the complete task(transformation and also Action).

**What is DAG and flow graph explain its role in compilation?**

**Directed Acyclic Graph (DAG) is a tool that depicts the structure of basic blocks, helps to see the flow of values flowing among the basic blocks, and offers optimization too**. DAG provides easy transformation on basic blocks. DAG can be understood here: Leaf nodes represent identifiers, names or constants.

**What is a directed graph in computer science?**

A directed graph (or digraph) is **a set of vertices and a collection of directed edges that each connects an ordered pair of vertices**. We say that a directed edge points from the first vertex in the pair and points to the second vertex in the pair.

**Is a directed graph complete?**

A directed graph having no multiple edges or loops (corresponding to a binary adjacency matrix with 0s on the diagonal) is called a simple directed graph. **A complete graph in which each edge is bidirected is called a complete directed graph**.

**What is directed path in graph theory?**

A directed path (sometimes called dipath) in a directed graph is **a finite or infinite sequence of edges which joins a sequence of distinct vertices, but with the added restriction that the edges be all directed in the same direction**.

**What is a strongly connected directed graph?**

(definition) Definition: **A directed graph that has a path from each vertex to every other vertex**. Formal Definition: A directed graph D=(V, E) such that for all pairs of vertices u, v ∈ V, there is a path from u to v and from v to u.

**Is a directed acyclic graph a tree?**

**A polytree (or directed tree or oriented tree or singly connected network) is a directed acyclic graph (DAG) whose underlying undirected graph is a tree**. A polyforest (or directed forest or oriented forest) is a directed acyclic graph whose underlying undirected graph is a forest.

**What is BFS and DFS?**

**BFS stands for Breadth First Search.** **DFS stands for Depth First Search**. 2. BFS(Breadth First Search) uses Queue data structure for finding the shortest path. DFS(Depth First Search) uses Stack data structure.

**How do you check if a directed graph is a tree?**

** For a directed graph: **

- Find the vertex with no incoming edges (if there is more than one or no such vertex, fail).
- Do a breadth-first or depth-first search from that vertex. …
- If you’re done and there are unexplored vertices, it’s not a tree – the graph is not connected.
- Otherwise, it’s a tree.

**What is Indegree and Outdegree?**

**The outdegree of a vertex is the number of arcs going out of it, the indegree of a vertex is the number of arcs going to it** (or into it, if you prefer). #

**What is Indegree and Outdegree of a node?**

The degree of a node in an undirected graph is the number of edges incident on it; for directed graphs **the indegree of a node is the number of edges leading into that node and its outdegree, the number of edges leading away from it** (see also Figures 6.1 and 6.2).

**Can a directed graph be complete?**

A directed graph having no multiple edges or loops (corresponding to a binary adjacency matrix with 0s on the diagonal) is called a simple directed graph. **A complete graph in which each edge is bidirected is called a complete directed graph**.

**What is a lineage graph?**

In Spark, Lineage Graph is **a dependencies graph in between existing RDD and new RDD**. It means that all the dependencies between the RDD will be recorded in a graph, rather than the original data.

**What is difference between DAG and lineage in Spark?**

**RDD Lineage is just a portion of a DAG (one or more operations) that lead to the creation of that particular RDD**. So, one DAG (one Spark program) might create multiple RDDs, and each RDD will have its lineage (i.e that path in your DAG that lead to that RDD).

**What is lineage and how it works in RDD and DataFrame?**

RDD lineage is nothing but **the graph of all the parent RDDs of an RDD**. We also call it an RDD operator graph or RDD dependency graph. To be very specific, it is an output of applying transformations to the spark. Then, it creates a logical execution plan.

**Is directed acyclic graph a tree?**

**A polytree (or directed tree or oriented tree or singly connected network) is a directed acyclic graph (DAG) whose underlying undirected graph is a tree**. A polyforest (or directed forest or oriented forest) is a directed acyclic graph whose underlying undirected graph is a forest.

**What is directed acyclic graph in spark?**

Directed Acyclic Graph is **an arrangement of edges and vertices**. In this graph, vertices indicate RDDs and edges refer to the operations applied on the RDD. According to its name, it flows in one direction from earlier to later in the sequence. When we call an action, the created DAG is submitted to DAG Scheduler.

**What are the essential properties of a flow graph in DAA?**

** A flow in G is a real-valued function f: V x V→R such that the following properties hold: **

- Capacity Constraint: For all u, v ∈ V, we need f (u, v) ≤ c (u, v).
- Skew Symmetry: For all u, v ∈ V, we need f (u, v) = – f (u, v).
- Flow Conservation: For all u ∈ V-{s, t}, we need.

**How do you describe a directed graph?**

A directed graph is graph, i.e., **a set of objects (called vertices or nodes) that are connected together, where all the edges are directed from one vertex to another**.

**How do you tell if a graph is directed?**

**Directed graphs have edges with direction**. The edges indicate a one-way relationship, in that each edge can only be traversed in a single direction. This figure shows a simple directed graph with three nodes and two edges.