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Bohmian Quantum Gravity and Cosmology
Published in Xavier Oriols, Jordi Mompart, Applied Bohmian Mechanics, 2019
Nelson Pinto-Neto, Ward Struyve
In conclusion, in Bohmian loop quantum cosmology, there is no big bang or big crunch singularity regardless of the wave function. The result follows from a very simple dynamical analysis. It is in agreement with the results derived in the standard quantum mechanical framework [21–23]. However, in [21–23], φ is considered a time variable from the start, whereas in the Bohmian case, φ can only be used as a clock variable when it increases monotonically with t. In addition, often only a special class of wave functions is considered, namely the ones that behave classically at “late times.”
On solving the densest k-subgraph problem on large graphs
Published in Optimization Methods and Software, 2020
Our final set of experiments consider graphs from the collaboration networks database. CA-GrQc collaboration network from [38] covers scientific collaborations between authors of papers that are submitted to General Relativity and Quantum Cosmology category. The data covers papers in the period of 124 months i.e. from January 1993 to April 2003. The adjacency matrix of the graph has 5242 vertices and 14,496 edges. We are not aware of an optimal value for the densest k-subgraph problem on CA-GrQc. Therefore, we present our results for different k, see Table 6. In the row denoted by CA-GrQc we list for each k the best computed objective value and the corresponding computational time in seconds. All results are obtained using the same settings: 200 simultaneous updates and 3000 iterations per round. Note that for k=10,20,30,40 we find the optimal cliques. In all those cases we needed to restart the algorithm at most 4 times. For k=50 we could not find a clique, and the best solution found is equal to 2146.
TsFSIM: a three-step fast selection algorithm for influence maximisation in social network
Published in Connection Science, 2021
Liqing Qiu, Shiqi Sai, Xiangbo Tian
Net-HEPT. The dataset is from the “High Energy Physics Theory” (HEPT) section with papers from 1991 to 2003.Wiki-Vote. The network contains all the Wikipedia voting data from the inception of Wikipedia till January 2008.CA-GrQc. This social network covers the “General Relativity and Quantum Cosmology” (Gr-Qc) section of the e-print arXiv.CA-HepPh. This collaboration network is from the e-print arXiv and covers scientific collaborations between authors papers submitted to High Energy Physics -- Phenomenology category. The data covers papers in the period from January 1993 to April 2003 (124 months).p2p-Gnutella31. This data set is Gnutella network collected in August 2002.CA-CondMat. This collaboration network is from the e-print arXiv and covers scientific collaborations between authors papers submitted to Condense Matter category. The data covers papers in the period from January 1993 to April 2003 (124 months).com-Youtube. This data set is from Youtube. In the Youtube social network, users form friendship each other and users can create groups which other users can join. And this social network has 8385 groups.