Eulerian cycle. Modified 2 years, 1 month ago. Viewed 6k times. 1. From the way I understand it: (1) a trail is Eulerian if it contains every edge exactly once. (2) a graph has a closed Eulerian trail iff it is connected and every vertex has even degree. (3) a complete bipartite graph has two sets of vertices in which the vertices in each set never form an ...

How does the following graph have an Euler tour and not every node has degree that is even? 1. Proof for euler graph. 0. Clarification in the proof that every eulerian graph must have vertices of even degree. 3. A connected graph has an Euler circuit if and only if every vertex has even degree. 1.

Eulerian cycle. After this conversion is performed, we must find a path in the graph that visits every edge exactly once. If we are to solve the "extra challenge," then we must find a cycle that visits every edge exactly once. This graph problem was solved in 1736 by Euler and marked the beginning of graph theory. The problem is thus commonly referred to as an Euler path (sometimes Euler tour) or Euler ...

1 Answer. Well, since an Eulerian cycle exists if and only if the degree of every vertex in a connected graph is even, we only need to check how many states it is possible to get to with one move (if a state is a vertex in our graph, then a move from one state to the next is an edge). In a Rubik's cube, we can get to a new state by rotating any ...

Question: Which graphs are Eulerian? 2 4 4 4 4 4 2 2 5 5 2 4 2 5 5 2 4 4 2 6 4 2 4 4 4 2 The degree of a node in a graph is the number of edges touching it (equivalently, the number of nodes it's adjacent to). Theorem: An (undirected) graph G is Eulerian if and only if it is connected and every node has even degree.Such a sequence of vertices is called a hamiltonian cycle. The first graph shown in Figure 5.16 both eulerian and hamiltonian. The second is hamiltonian but not eulerian. Figure …

At this point We need to prove that the answer contains every edge exactly once (that is, the answer is Eulerian), and this follows from the fact that every edge is explored at most once, since it gets removed from the graph whenever it is picked, and from the fact that the algorithm works as a DFS, therefore it explores all edges and each time ...An Eulerian path is a result of a graph traversal from one node to another that includes all edges in the graph (nodes can be visited multiple times). Answer the following questions about the graphs. If you cannot see the picture, please use the pdf file EulerianGraphs.pdf posted under Files/Final Graph 1. Graph 2. Graph 3.A graph G is even-cycle decomposable if its edge set can be partitioned into even cycles. Note that if G is even-cycle decomposable, then necessarily G is Eulerian, loopless, and |E(G)| is even. For bipartite graphs, these conditions are also sufficient, since every cycle is even. Proposition 1.1 (Euler). Every Eulerian bipartite graph is even ...Euler path = BCDBAD. Example 2: In the following image, we have a graph with 6 nodes. Now we have to determine whether this graph contains an Euler path. Solution: The above graph will contain the Euler path if each edge of this graph must be visited exactly once, and the vertex of this can be repeated.Urmând muchiile în ordine alfabetică, se poate găsi un ciclu eulerian. În teoria grafurilor, un drum eulerian (sau lanț eulerian) este un drum într-un graf finit, care vizitează fiecare muchie exact o dată. În mod similar, un „ ciclu eulerian ” sau „ circuit eulerian ” este un drum eulerian traseu care începe și se termină ...Draw a Bipartite Graph with 10 vertices that has an Eulerian Path and a Hamiltonian. Draw an undirected graph with 6 vertices that has an Eulerian Cycle and a Hamiltonian Cycle. The degree of each vertex must be greater than 2. List the degrees of the vertices, draw the Hamiltonian Cycle on the graph and give the vertex list of the Eulerian Cycle.ISBN: 9780547587776. Author: HOLT MCDOUGAL. Publisher: HOLT MCDOUGAL. SEE MORE TEXTBOOKS. Solution for For the graphs shown below: Determine if it's Hamiltonian or Eulerian. If the graph is Hamiltonian, find Hamilton Cycle; if the graph is Eulerian,….TOPICS. Algebra Applied Mathematics Calculus and Analysis Discrete Mathematics Foundations of Mathematics Geometry History and Terminology Number Theory Probability and Statistics Recreational Mathematics Topology Alphabetical Index New in MathWorldreversal. We normally treat an eulerian cycle as a specific closed eulerian walk, but with the understanding that any other member of the equivalence class could equally well be used. Note that the subgraph spanned by the set of vertices and edges of an eulerian cycle need not be a cycle in the usual sense, but will be an eulerian subgraph of X.

List the degrees of the vertices, draw the Hamiltonian Cycle on the graph and provide justification that there is no E.C. and no E.P. Draw a Complete Graph, Kn, with n > 5 that has a Hamiltonian Cycle and has an Eulerian Cycle. List the degrees of the vertices, draw the Hamiltonian Cycle on the graph and give the vertex list of the Eulerian Cycle.Apply Fleury's algorithm beginning with vertex K, to find an Eulerian path in the following graph. In applying the algorithm, at each stage chose the edge (from those available) which visits the vertex which comes first in alphabetical order. Which of the edges are bridges? Does the graph have Eulerian path?Eulerian cycle (circuit)? Now apply ...2. Definitions. Both Hamiltonian and Euler paths are used in graph theory for finding a path between two vertices. Let's see how they differ. 2.1. Hamiltonian Path. A Hamiltonian path is a path that visits each vertex of the graph exactly once. A Hamiltonian path can exist both in a directed and undirected graph.

That means that Eulerian cycles can only differ by edge's order (I propose to exclude edge's cyclical permutations as trivial option). It is possible to find Eulerian cycle, using Fleury's algorithm: in short, move as you like (throwing out the edges you went on), but do not cross the bridge until the whole component is done.

The de Bruijn sequence for alphabet size k = 2 and substring length n = 2.In general there are many sequences for a particular n and k but in this example it is unique, up to cycling.. In combinatorial mathematics, a de Bruijn sequence of order n on a size-k alphabet A is a cyclic sequence in which every possible length-n string on A occurs exactly once as a substring (i.e., as a contiguous ...

9. Show that any graph where the degree of every vertex is even has an Eulerian cycle. Show that if there are exactly two vertices aand bof odd degree, there is an Eulerian path from a to b. Show that if there are more than two vertices of odd degree, it is impossible to construct an Eulerian path. 10.Mar 24, 2023 · Cycle detection is a particular research field in graph theory. There are algorithms to detect cycles for both undirected and directed graphs. There are scenarios where cycles are especially undesired. An example is the use-wait graphs of concurrent systems. In such a case, cycles mean that exists a deadlock problem. De nition 2.4. An Eulerian circuit on a graph is a circuit that uses every edge. What Euler worked out is that there is a very simple necessary and su cient condition for an Eulerian circuit to exist. Theorem 2.5. A graph G = (V;E) has an Eulerian circuit if and only if G is connected and every vertex v 2V has even degree d(v).Q: For which range of values for n the new graph has Eulerian cycle? We know that in order for a graph to have an Eulerian cycle we must prove that d i n = d o u t for each vertex. I proved that for the vertex that didn't get affected by this change d i n = d o u t = 2. But for the affected ones, that's not related to n and always d i n isn't ...

For each graph find each of its connected components. discrete math. A graph G has an Euler cycle if and only if G is connected and every vertex has even degree. 1 / 4. Find step-by-step Discrete math solutions and your answer to the following textbook question: For which values of m and n does the complete bipartite graph $$ K_ {m,n} $$ have ...Questions tagged [eulerian-path] Ask Question. This tag is for questions relating to Eulerian paths in graphs. An "Eulerian path" or "Eulerian trail" in a graph is a walk that uses each edge of the graph exactly once. An Eulerian path is "closed" if it starts and ends at the same vertex. Learn more….The Eulerian Cycle Decomposition Conjecture, by Chartrand, Jordon and Zhang, states that if the minimum number of odd cycles in a cycle decomposition of an Eulerian graph G of size m is a, the maximum number of odd cycles in such a cycle decomposition is b and ℓ is an integer such that a ≤ ℓ ≤ b where ℓ and m are of the same parity ...Problem Description. Implement the Hierholzer's algorithm for finding Eulerian cycles. Construct some directed graph that has an Eulerian cycle, and then use the implemented algorithm to find that cycle. Eulerian path: Hierholzer's algorithm - wikipedia.org.Figure 6.3.1 6.3. 1: Euler Path Example. One Euler path for the above graph is F, A, B, C, F, E, C, D, E as shown below. Figure 6.3.2 6.3. 2: Euler Path. This Euler path travels every edge once and only once and starts and ends at different vertices. This graph cannot have an Euler circuit since no Euler path can start and end at the same ...Aug 13, 2021 Eulerian Cycles and paths are by far one of the most influential concepts of graph theory in the world of mathematics and innovative technology. These circuits and paths were first discovered by Euler in 1736, therefore giving the name "Eulerian Cycles" and "Eulerian Paths."Add a comment. 2. a graph is Eulerian if its contains an Eulerian circuit, where Eulerian circuit is an Eulerian trail. By eulerian trail we mean a trail that visits every edge of a graph once and only once. now use the result that "A connectded graph is Eulerian if and only if every vertex of G has even degree." now you may distinguish easily.An Eulerian cycle of a multigraph G is a closed chain in which each edge appears exactly once. Euler showed that a multigraph possesses an Eulerian cycle if and only if …The de Bruijn graph B for k = 4 and a two-character alphabet composed of the digits 0 and 1. This graph has an Eulerian cycle because each node has indegree and outdegree equal to2. Following the ...Math. Advanced Math. Advanced Math questions and answers. 1. (16p) Consider the following graph: Consider the following graph: c E к (a) is this graph Eulerian? If so, find an Eulerian cycle. (b) Does this graph have an Eulerian circuit? If so, find one. (c) Does this graph have a Hamiltonian cycle? If so, find one.the cycle. Proof of the theorem (continued) We proceed by induction on the number of edges. Base case: 0 edge, the graph is Eulerian. Induction hypothesis: A graph with at most n edges is Eulerian. Induction step: If all vertices have degree 2, the graph is a cycle (we proved it last week) and it is Eulerian. Otherwise, let G' be the graphFor odd n, by Euler's theorem implies that it is not Eulerian. Share. Cite. Follow answered Nov 29, 2016 at 0:57. Thomas Edison Thomas Edison. 784 7 7 silver badges 19 19 bronze badges ... Algorithm that check if given undirected graph can have Eulerian Cycle by adding edges. Hot Network Questions What are the possibilities for travel by train ...An Eulerian cycle can be found using FindEulerianCycle: A connected undirected graph is Eulerian iff every graph vertex has an even degree: A connected undirected graph is Eulerian if it can be decomposed into edge disjoint cycles:Euler's cycle or circuit theorem shows that a connected graph will have an Euler cycle or circuit if it has zero odd vertices. Euler's sum of degrees theorem shows that however many edges a ...a cycle that visits every edge of a de Bruijn graph exactly once, i.e., an Eulerian cycle. The answer to the question Every Eulerian cycle in a de Bruijn graph or a Hamiltonian cycle in an overlap graph corre-sponds to a single genome reconstruction where all the repeats (long sequences that appearNov 29, 2017 · 10. It is not the case that every Eulerian graph is also Hamiltonian. It is required that a Hamiltonian cycle visits each vertex of the graph exactly once and that an Eulerian circuit traverses each edge exactly once without regard to how many times a given vertex is visited. Take as an example the following graph: Draw a Bipartite Graph with 10 vertices that has an Eulerian Path and a Hamiltonian. Draw an undirected graph with 6 vertices that has an Eulerian Cycle and a Hamiltonian Cycle. The degree of each vertex must be greater than 2. List the degrees of the vertices, draw the Hamiltonian Cycle on the graph and give the vertex list of the Eulerian Cycle.What do Eulerian and Hamiltonian cycles have to do with genome assembly? Paul Medvedev , Mihai Pop x Published: May 20, 2021 https://doi.org/10.1371/journal.pcbi.1008928 Article Authors Metrics Comments Media Coverage Abstract Introduction The answer to the question Formal statement and proof of main theorem Conclusions Endnotes AcknowledgmentsThe book gives a proof that if a graph is connected, and if every vertex has even degree, then there is an Euler circuit in the graph. Buried in that proof is a ...

You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: Determine whether the following graph contains any Eulerian cycles (and provide an example of an Eulerian cycle if so; do not provide all cycles) and explain briefly how you found them. V = (p,q,r,s,t,u,v,w) E = { (p,q), (q,r), (r,s) , p, s ...This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: Give a condition that is sufficient but not necessary for an undirected graph not to have an Eulerian Cycle. Justify your answer. Give a condition that is sufficient but not necessary for an undirected graph ...At each vertex of K5 K 5, we have 4 4 edges. A circuit is going to enter the vertex, leave, enter, and leave again, dividing up the edges into two pairs. There are 12(42) = 3 1 2 ( 4 2) = 3 ways to pair up the edges, so there are 35 = 243 3 5 = 243 ways to make this decision at every vertex. Not all of these will correspond to an Eulerian ...and a closed Euler trial is called an Euler tour (or Euler circuit). A graph is Eulerian if it contains an Euler tour. Lemma 4.1.2: Suppose all vertices of G are even vertices. Then G can be partitioned into some edge-disjoint cycles and some isolated vertices. Theorem 4.1.3: A connected graph G is Eulerian if and only if each vertex in G is of ...I've been trying to implement Hierholzer's algorithm into code using Python since 5 days. My experience with graph theory is also 5 days so far. My codes are below: def cycle (D1): import random key = list (D1.keys ()) ran_k = random.choice (key) tmp_stk = [] tmp_stk += [ran_k] r_stack = [] if len (D1 [ran_k]) > 1: tmp_stk += [D1 [ran_k] [0 ...To check if your undirected graph has a Eulerian circuit with an adjacency list representation of the graph, count the number of vertices with odd degree. This is where you can utilize your adjacency list. If the odd count is 0, then check if all the non-zero vertices are connected. You can do this by using DFS traversals.Math. Advanced Math. Advanced Math questions and answers. 1. (16p) Consider the following graph: Consider the following graph: c E к (a) is this graph Eulerian? If so, find an Eulerian cycle. (b) Does this graph have an Eulerian circuit? If so, find one. (c) Does this graph have a Hamiltonian cycle? If so, find one.An Eulerian cycle is a closed walk that uses every edge of G G exactly once. If G G has an Eulerian cycle, we say that G G is Eulerian. If we weaken the requirement, and do not require the walk to be closed, we call it an Euler path, and if a graph G G has an Eulerian path but not an Eulerian cycle, we say G G is semi-Eulerian. 🔗.

Eulerian circuits Characterization Theorem For a connected graph G, the following statements are equivalent: 1 G is Eulerian. 2 Every vertex of G has even degree. 3 The …Nov 8, 2011 · This implies that the ant has completed a cycle; if this cycle happens to traverse all edges, then the ant has found an Eulerian cycle! Otherwise, Euler sent another ant to randomly traverse unexplored edges and thereby to trace a second cycle in the graph. Euler further showed that the two cycles discovered by the two ants can be combined into ... First, take an empty stack and an empty path. If all the vertices have an even number of edges then start from any of them. If two of the vertices have an odd number of edges then start from one of them. Set variable current to this starting vertex. If the current vertex has at least one adjacent node then first discover that node and then ...An Eulerian cycle is a cycle in a graph that traverses every edge of the graph exactly once. The Eulerian cycle is named after Leonhard Euler, ...Mar 11, 2013 · Add a comment. 2. a graph is Eulerian if its contains an Eulerian circuit, where Eulerian circuit is an Eulerian trail. By eulerian trail we mean a trail that visits every edge of a graph once and only once. now use the result that "A connectded graph is Eulerian if and only if every vertex of G has even degree." now you may distinguish easily. Secondly, there do exist Eulerian multigraphs on 11 vertices with 53 edges: For example, take a cycle of length 11 (11 edges). Now between two consecutive vertices, place $42$ edges. Then each vertex has even degree (either $2$ or $44$) and so this graph is Eulerian.I've been trying to implement Hierholzer's algorithm into code using Python since 5 days. My experience with graph theory is also 5 days so far. My codes are below: def cycle (D1): import random key = list (D1.keys ()) ran_k = random.choice (key) tmp_stk = [] tmp_stk += [ran_k] r_stack = [] if len (D1 [ran_k]) > 1: tmp_stk += [D1 [ran_k] [0 ...FindEulerianCycle [ { v w, … }, …] uses rules v w to specify the graph g. Details Background & Context Examples open all Basic Examples (2) Find an Eulerian cycle: In [1]:= In [2]:= Out [2]= Show the cycle: In [3]:= Out [3]= Find several Eulerian cycles: In [1]:= Out [1]= Scope (8) Applications (7) Properties & Relations (6) Neat Examples (1)有两种欧拉路。. 第一种叫做 Eulerian path (trail),沿着这条路径走能够走遍图中每一条边;第二种叫做 Eularian cycle,沿着这条路径走,不仅能走遍图中每一条边,而且起点和终点都是同一个顶点。. 注意:欧拉路要求每条边只能走一次,但是对顶点经过的次数没有 ...Start with an empty stack and an empty circuit (eulerian path). If all vertices have even degree: choose any of them. This will be the current vertex. If there are exactly 2 vertices having an odd degree: choose one of them. This will be the current vertex. Otherwise no Euler circuit or path exists.Thoroughly justify your answer. c) Find a Hamiltonian Cycle starting at vertex A. Draw the Hamiltonian Cycle on the graph and list the vertices of the cycle. Note: A Hamiltonian Cycle is a simple cycle that traverses all vertices. A simple cycle starts at a vertex, visits other vertices once then returns to the starting vertex.$\begingroup$ For (3), it is known that a graph has an eulerian cycle if and only if all the nodes have an even degree. That's linear on the number of nodes. $\endgroup$ – frabala. Mar 18, 2019 at 13:52 ... It is even possible to find an Eulerian path in linear time (in the number of edges).Theorem 1 : A non-trivial connected graph G is Eulerian if and only if every vertex of G has even degree. i. A non triv …. n-cube is a graph with 2" vertices, each corresponding to a n-bit string. Two vertices has an edge if the corresponding …{"payload":{"allShortcutsEnabled":false,"fileTree":{"scripts/bioinformatics-textbook-track":{"items":[{"name":"BA10A.py","path":"scripts/bioinformatics-textbook-track ...This is known as Euler's Theorem: A connected graph has an Euler cycle if and only if every vertex has even degree. The term Eulerian graph has two common meanings in graph theory. One meaning is a graph with an Eulerian circuit, and the other is a graph with every vertex of even degree.Q: For which range of values for n the new graph has Eulerian cycle? We know that in order for a graph to have an Eulerian cycle we must prove that d i n = d o u t for each vertex. I proved that for the vertex that didn't get affected by this change d i n = d o u t = 2. But for the affected ones, that's not related to n and always d i n isn't ...Nov 8, 2011 · This implies that the ant has completed a cycle; if this cycle happens to traverse all edges, then the ant has found an Eulerian cycle! Otherwise, Euler sent another ant to randomly traverse unexplored edges and thereby to trace a second cycle in the graph. Euler further showed that the two cycles discovered by the two ants can be combined into ... Teruskan proses diatas untuk semua cycle dalam G sehingga akhir dari proses diperoleh path tertutup yang memuat semua edge dari G. Dengan demikian, G meru- pakan Eulerian. Akibat 2.1.8 (Wilson, 1996) Suatu connected graph G adalah semi Eulerian jika dan hanya jika G mempunyai tepat dua verteks dengan degree ganjil.

Computer Science questions and answers. a 5. Construct a complete bipartite graph with at least 4 vertices, that does not have a Hamiltonian Cycle, nor a Hamiltonian Path, nor an Eulerian Cycle, nor an Eulerian Path. List the degrees of the vertices and justify your answer. STA.

The de Bruijn sequences can be constructed by taking a Hamiltonian path of an n-dimensional de Bruijn graph over k symbols (or equivalently, an Eulerian cycle of an (n − 1)-dimensional de Bruijn graph). An alternative construction involves concatenating together, in lexicographic order, all the Lyndon words whose length divides n.

Given a graph that has to Eulerian cycle, write a function which back and cycle in tuple form. I came up through followers solution for get problem and am stuck trying to perform it faster. Do you h...You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: Determine whether the following graph contains any Eulerian cycles (and provide an example of an Eulerian cycle if so; do not provide all cycles) and explain briefly how you found them. V = (p,q,r,s,t,u,v,w) E = { (p,q), (q,r), (r,s) , p, s ...Eulerian Cycle: An undirected graph has Eulerian cycle if following two conditions are true. All vertices with non-zero degree are connected. We don’t care about vertices with zero degree because they don’t belong to Eulerian Cycle or Path (we only consider all edges).Draw an undirected graph with 6 vertices that has an Eulerian Cycle and a Hamiltonian Cycle. The degree of each vertex must be greater than 2. List the degrees of the vertices, draw the Hamiltonian Cycle on the graph and give the vertex list of the Eulerian Cycle. Draw a Bipartite Graph with 10 vertices that has an Eulerian Path and a Hamiltonian.Question: Ex.2 (Euler's tour) In graph theory, an Eulerian path is a path in a finite graph G that visits every edge exactly once (allowing for revisiting vertices). Similarly, an Eulerian cycle is an Eulerian path that starts and ends on the same vertex. These were first discussed by Leonhard Euler while solving the famous Seven Bridges of Königsberg problem in 1736No graph of order 2 is Eulerian, and the only connected Eulerian graph of order 4 is the 4-cycle with (even) size 4. The only possible degrees in a connected Eulerian graph of order 6 are 2 and 4. Any such graph with an even number of vertices of degree 4 has even size, so our graphs must have 1, 3, or 5 vertices of degree 4. Up to isomorphism ...$\begingroup$ For (3), it is known that a graph has an eulerian cycle if and only if all the nodes have an even degree. That's linear on the number of nodes. $\endgroup$ – frabala. Mar 18, 2019 at 13:52 ... It is even possible to find an Eulerian path in linear time (in the number of edges).An Eulerian path is a path that goes through every edge once. Similarly, an Eulerian cycle is an Eulerian path that starts and ends with the same node. An important condition is that a graph can have an Eulerian cycle (not path!) if and only if every node has an even degree. Now, to find the Eulerian cycle we run a modified DFS.

cagilpaulmarkhamfuel pump dodge ramcrna school kansas city Eulerian cycle kansas jayhawk men's basketball schedule [email protected] & Mobile Support 1-888-750-6599 Domestic Sales 1-800-221-3402 International Sales 1-800-241-7268 Packages 1-800-800-4133 Representatives 1-800-323-4228 Assistance 1-404-209-8255. This is a C++ Program to check whether graph contains Eulerian Path. The criteran Euler suggested, 1. If graph has no odd degree vertex, there is at least one Eulerian Circuit. 2. If graph as two vertices with odd degree, there is no Eulerian Circuit but at least one Eulerian Path. 3.. kansas golf scores a cycle that visits every edge of a de Bruijn graph exactly once, i.e., an Eulerian cycle. The answer to the question Every Eulerian cycle in a de Bruijn graph or a Hamiltonian cycle in an overlap ...Jun 26, 2023 · A Eulerian cycle is a Eulerian path that is a cycle. The problem is to find the Eulerian path in an undirected multigraph with loops. Algorithm¶ First we can check if there is an Eulerian path. We can use the following theorem. An Eulerian cycle exists if and only if the degrees of all vertices are even. ou vs osu softball today2014 chevy silverado radiator fan wont shut off Eulerian cycle-accessible all node once and again,compulsory cross every node while Hamiltonian cycle-node must be pass through once only ,can skip node. - user6788. Feb 9, 2011 at 11:10. No, Eulerian cycles use all edges and return to start. Hamiltonian cycles use all vertices once each and return to start. - Ross Millikan. what is a 4.5 gpa on a 4.0 scalejacque vaughn coach New Customers Can Take an Extra 30% off. There are a wide variety of options. 5. Each connected component of a graph G G is Eulerian if and only if the edges can be partitioned into disjoint sets, each of which induces a simple cycle in G G. Proof by induction on the number of edges. Assume G G has n ≥ 0 n ≥ 0 edges and the statement holds for all graphs with < n < n edges. If G G has more than one connected ...Given it seems to be princeton.cs.algs4 course task I am not entirely sure what would be the best answer here. I'd assume you are suppose to learn and learning limited number of things at a time (here DFS and euler cycles?) is pretty good practice, so in terms of what purpose does this code serve if you wrote it, it works and you understand …the cycle. Proof of the theorem (continued) We proceed by induction on the number of edges. Base case: 0 edge, the graph is Eulerian. Induction hypothesis: A graph with at most n edges is Eulerian. Induction step: If all vertices have degree 2, the graph is a cycle (we proved it last week) and it is Eulerian. Otherwise, let G' be the graph