15.05.2026 | Network Robustness

A cybersecurity expert is evaluating the vulnerabilities of a communication grid mapped as a scale-free network. He observes that while the grid survives random router failures effortlessly, it collapses quickly when a very small fraction of specific high-degree routers is targeted. What explains this behavior?

A) Targeted attacks uniquely decrease the minimum degree of the network, causing a cascading failure among low-degree nodes.
B) Targeted attacks on scale-free networks automatically convert their topology into a random Erdos-Renyi network, which cannot sustain a giant component.
C) The attack threshold ($f_c$) for scale-free networks is theoretically proven to be higher than the threshold for random failures.
D) Removing a fraction of the hubs significantly lowers the maximum degree of the network and alters the degree distribution, meaning that even removing a tiny fraction of hubs can destroy the network.
E) None of the above.

Original idea by: Yuri S. Costa

Comentários

Postar um comentário

Postagens mais visitadas deste blog

13.03.2026 | BFS

Imagem
Consider the following statements regarding a Breadth-First Search (BFS) traversal of the graph. Assume that whenever multiple neighbor nodes are available for expansion, they are selected in ascending numerical order : I. The BFS traversal path when starting from node 1 is: 2-4-6-3-7-9-10-5-8.  II. Nodes 5 and 8 are the furthest from node 1, just as node 1 is the furthest node when the search is initiated from either node 5 or 8. III. Adding an edge between nodes 9 and 8 alters the path when expanding from node 1, causing node 8 to be discovered before node 5. IV. Adding a new edge between nodes 2 and 7 makes no difference to the generated path when starting the expansion from node 1. The alternative that represents the correct statements is: a) Only statements I and II are correct. b) Only statements I, III, and IV are correct. c) Only statements II and IV are correct. d) Only statements IIII and IV are correct. e) None of the above. Original idea by: Yuri S. Costa
Leia mais

06.03.2026 | Graph Theory

Imagem
Observe the graph below and choose the correct alternative. Consider the following statements:   I. There are two bridges and two strongly connected components. II. Removing node A results in a graph with no strongly connected components. III. Creating the link HE results in a new strongly connected component. IV. Removing the link IA transforms the graph into a disconnected graph. The alternative that represents the correct statements is: a) Only statements I and II are correct. b) Only statements II and IV are correct. c) Only statements II, III, and IV are correct. d) Only statements I, III, and IV are correct. e) None of the above. Original idea by: Yuri S. Costa
Leia mais

10.04.2026 | Network Flow

Imagem
 In the study of Network Flow, the Ford-Fulkerson algorithm relies on constructing a Residual Network $R_f$ from an original flow network $G$ and a valid flow $f$ . Below is the Residual Graph ( $R_f$ ) generated from an unknown flow network. Which of the following pairs of Original Network $G$ (left) and Flow $f$ (right) correctly generated the Residual Graph above? Pair I: Pair II: Pair III: Pair IV: The alternative that represents the correct statement is: a) Only pair II is correct. b) Only pairs I and III are correct. c) Only pairs II and IV are correct. d) Only pair I is correct. e) None of the above. Original idea by: Yuri S. Costa
Leia mais