41 citations · 93 across the 11 of their papers we have counts for
13 papers
Multiscale Euclidean Network Trajectories: Second-Moment Geometry, Attribution, and Change Points
Haruka Ezoe, Ryohei Hisano
Understanding a dynamic network requires more than locating when it changes: we also want to know the magnitude and structural direction of change and which nodes contribute. Unfol…
Nondiagonal Mixture of Dirichlet Network Distributions for Analyzing a Stock Ownership Network
Wenning Zhang, Ryohei Hisano, Takaaki Ohnishi +1
Block modeling is widely used in studies on complex networks. The cornerstone model is the stochastic block model (SBM), widely used over the past decades. However, the SBM is limi…
Gaussian Hierarchical Latent Dirichlet Allocation: Bringing Polysemy Back
Takahiro Yoshida, Ryohei Hisano, Takaaki Ohnishi
Topic models are widely used to discover the latent representation of a set of documents. The two canonical models are latent Dirichlet allocation, and Gaussian latent Dirichlet al…
Identifying the Hierarchical Influence Structure Behind Smart Sanctions Using Network Analysis
Ryohei Hisano, Hiroshi Iyetomi, Takayuki Mizuno
Smart sanctions are an increasingly popular tool in foreign policy. Countries and international institutions worldwide issue such lists to sanction targeted entities through financ…
Prediction of ESG Compliance using a Heterogeneous Information Network
Ryohei Hisano, Didier Sornette, Takayuki Mizuno
Negative screening is one method to avoid interactions with inappropriate entities. For example, financial institutions keep investment exclusion lists of inappropriate firms that…
Learning Topic Models by Neighborhood Aggregation
Ryohei Hisano
Topic models are frequently used in machine learning owing to their high interpretability and modular structure. However, extending a topic model to include a supervisory signal, t…
Semi-supervised Graph Embedding Approach to Dynamic Link Prediction
Ryohei Hisano
We propose a simple discrete time semi-supervised graph embedding approach to link prediction in dynamic networks. The learned embedding reflects information from both the temporal…
The gradual evolution of buyer--seller networks and their role in aggregate fluctuations
Ryohei Hisano, Tsutomu Watanabe, Takayuki Mizuno +2
Buyer--seller relationships among firms can be regarded as a longitudinal network in which the connectivity pattern evolves as each firm receives productivity shocks. Based on a da…
A New Approach to Building the Interindustry Input--Output Table
Ryohei Hisano
We present a new approach to estimating the interdependence of industries in an economy by applying data science solutions. By exploiting interfirm buyer--seller network data, we s…
High quality topic extraction from business news explains abnormal financial market volatility
Ryohei Hisano, Didier Sornette, Takayuki Mizuno +2
Understanding the mutual relationships between information flows and social activity in society today is one of the cornerstones of the social sciences. In financial economics, the…
On the distribution of time-to-proof of mathematical conjectures
Ryohei Hisano, Didier Sornette
What is the productivity of Science? Can we measure an evolution of the production of mathematicians over history? Can we predict the waiting time till the proof of a challenging c…
Predicted and Verified Deviations from Zipf's law in Ecology of Competing Products
Ryohei Hisano, Didier Sornette, Takayuki Mizuno
Zipf's power-law distribution is a generic empirical statistical regularity found in many complex systems. However, rather than universality with a single power-law exponent (equal…
Sales Distribution of Consumer Electronics
Ryohei Hisano, Takayuki Mizuno
Using the uniform most powerful unbiased test, we observed the sales distribution of consumer electronics in Japan on a daily basis and report that it follows both a lognormal dist…