We introduce a new clustering algorithm, MulGuisin (MGS), that can identify distinct galaxy over-densities using topological information from the galaxy distribution. This algorithm was first introduced in an LHC experiment as a Jet Finder software, which looks for particles that clump together in close proximity. The algorithm preferentially considers particles with high energies and merges them only when they are closer than a certain distance to create a jet. MGS shares some similarities with the minimum spanning tree (MST) since it provides both clustering and network-based topology information. Also, similar to the density-based spatial clustering of applications with noise (DBSCAN), MGS uses the ranking or the local density of each particle to construct clustering. In this paper, we compare the performances of clustering algorithms using controlled data and some realistic simulation data as well as the SDSS observation data, and we demonstrate that our new algorithm finds networks most correctly and defines galaxy networks in a way that most closely resembles human vision.

Introduction
Methods
    MulGuisin Network Finding Algorithm
    Benchmark Algorithms
        Friends-of-Friends (FoF)
        Minimum Spanning Tree (MST)
        Density-Based Spatial Clustering of Applications with Noise (DBSCAN)
    A Simple 2D Toy Model Test
Data
    Controlled Random Data (D1–D3)
        Different Spatial Dispersion (D1)
        Additional Noisy Galaxies (D2)
        HOD-Based Mock Galaxies (D3-HOD)
    Realistic Data: SDSS & Horizon Run 4 (D4)
        Volume-Limited KIAS-VAGC (D4-SDSS)
        Horizon Run 4 (D4-HR4)
Results
    Results with Controlled Data
    Results with Observational and Cosmological Simulation Data
    Cluster Mass Function in Cosmological Simulation Data
Conclusions
Acknowledgments
References

• Young Ju(Department of Physics, University of Seoul, Seoul 02504, Republic of Korea, Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea)
• Inkyu Park(Department of Physics, University of Seoul, Seoul 02504, Republic of Korea, Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea) Corresponding author
• Cristiano G. Sabiu(Department of Physics, University of Seoul, Seoul 02504, Republic of Korea, Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea)
• Sungwook E. Hong(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea, Astronomy Campus, University of Science and Technology, Daejeon 34055, Republic of Korea)