A computing unit obtains a graph including nodes and edges and representing a communication condition at first timing and at second timing and detects an edge that is added between the first and second timing among the edges. The computing unit calculates probabilities of transmitting information from each node to nodes coupled to the added edge, selects a subset of the nodes based on the calculated probabilities, selects nodes included in the subset as the starting points of information, calculates first probabilities of transmitting information from the selected nodes to each node based on the graph obtained at the first timing and second probabilities of transmitting information from the selected nodes to each node based on the graph obtained at the second timing, and detects a change in the communication condition between the first and second timing by comparing the first probabilities with the second probabilities.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A communication condition change detection method comprising: obtaining a graph representing a communication condition at a first timing and at a second timing, the graph including a plurality of nodes representing information entities that transmit, forward, and receive information and a plurality of edges representing communication between the plurality of nodes; detecting an edge that is added between the first timing and the second timing among the edges; calculating, by a processor, probabilities that information is transmitted from each node to nodes coupled to the added edge; selecting a subset of the plurality of nodes based on the calculated probabilities; selecting nodes included in the subset as starting points of information; calculating first probabilities that information is transmitted from the selected nodes to each node based on the graph obtained at the first timing and second probabilities that information is transmitted from the selected nodes to each node based on the graph obtained at the second timing; and detecting a change in the communication condition between the first timing and the second timing by comparing the first probabilities with the second probabilities. 2. The communication condition change detection method according to claim 1, wherein: the obtaining includes detecting two or more added edges; and the calculating includes calculating probabilities that information is transmitted from each node to a plurality of nodes each coupled to any of the two or more added edges, and selecting the subset based on a highest probability among the probabilities calculated for each node serving as a starting point. 3. The communication condition change detection method according to claim 1, wherein: the obtaining includes detecting two or more added edges; and the calculating includes extracting an edge included in a subgraph that satisfies a predetermined condition from the two more added edges, and selecting nodes coupled to the extracted edge as end points of information, and calculating the probabilities that information is transmitted from each node. 4. The communication condition change detection method according to claim 3, wherein the calculating includes calculating, for each node serving as a starting point, a sum of the probabilities that information is transmitted to a plurality of nodes coupled to the extracted edge, and selecting the subset based on the sum. 5. The communication condition change detection method according to claim 3, wherein the subgraph that satisfies the predetermined condition is a clique having an edge between any two nodes to connect the two nodes. 6. An information processing apparatus for detecting a change of communication condition, the information processing apparatus comprising: a memory configured to store a graph representing a communication condition at a first timing and at a second timing, the graph including a plurality of nodes representing information entities that transmit, forward, and receive information and a plurality of edges representing communication between the plurality of nodes; and a processor configured to perform a process including: detecting an edge that is added between the first timing and the second timing among the edges, calculating probabilities that information is transmitted from each node to nodes coupled to the added edge, selecting a subset of the plurality of nodes based on the calculated probabilities, selecting nodes included in the subset as starting points of information, calculating first probabilities that information is transmitted from the selected nodes to each node based on the graph obtained at the first timing and second probabilities that information is transmitted from the selected nodes to each node based on the graph obtained at the second timing, and detecting a change in the communication condition between the first timing and the second timing by comparing the first probabilities with the second probabilities. 7. A non-transitory computer-readable storage medium storing a computer program that causes a computer to perform a process comprising: obtaining a graph representing a communication condition at a first timing and at a second timing, the graph including a plurality of nodes representing information entities that transmit, forward, and receive information and a plurality of edges representing communication between the plurality of nodes; detecting an edge that is added between the first timing and the second timing among the edges; calculating probabilities that information is transmitted from each node to nodes coupled to the added edge; selecting a subset of the plurality of nodes based on the calculated probabilities; selecting nodes included in the subset as starting points of information; calculating first probabilities that information is transmitted from the selected nodes to each node based on the graph obtained at the first timing and second probabilities that information is transmitted from the selected nodes to each node based on the graph obtained at the second timing; and detecting a change in the communication condition between the first timing and the second timing by comparing the first probabilities with the second probabilities.