50 citations · 141 across the 19 of their papers we have counts for
20 papers
Analysis of pairs in a generalized deck of playing cards
Ken Yamamoto, Satoshi Umeki
In this study, we analyze the number of pairs (i.e., two cards of the same rank) in a set of cards randomly selected from a deck of playing cards. While the standard deck of playin…
Quantifying defensive pressure on the ball carrier in soccer based on minimum arrival time
Takuma Narizuka, Ikuya Sakamoto, Ken Yamamoto +1
Defensive pressure on the ball carrier is a fundamental component of soccer tactics. Existing pressure measures often involve additional modeling assumptions, which may reduce inte…
Analysis of size distributions of fictional characters: from Pokémon to Godzilla
Ken Yamamoto
In this letter, the size (height and weight) of fictional characters in animations, superhero series, movies, and other media is studied. We find that the distributions of characte…
Theory and data analysis of player and team ball possession time in football
Ken Yamamoto, Seiya Uezu, Keiichiro Kagawa +2
In this study, the stochastic properties of player and team ball possession times in professional football matches are examined. Data analysis shows that player possession time fol…
Analysis and application of multiplicative stochastic process with a sample-dependent lower bound
Ken Yamamoto, Yoshihiro Yamazaki
A multiplicative stochastic process with the lower bound lognormally distributed is investigated. For the process, the model is constructed, and its distribution function (involvin…
Large deviation theorem for branches of the random binary tree in the Horton-Strahler analysis
Ken Yamamoto
The Horton-Strahler analysis is a graph-theoretic method to measure the bifurcation complexity of branching patterns, by defining a number called the order to each branch. The main…
Central limit theorem for the Horton-Strahler bifurcation ratio of general branch order
Ken Yamamoto
The Horton-Strahler ordering method, originating in hydrology, formulates the hierarchical structure of branching patterns using a quantity called the bifurcation ratio. The main r…
Analysis of a stochastic model for bacterial growth and the lognormality of the cell-size distribution
Ken Yamamoto, Jun-ichi Wakita
This paper theoretically analyzes a phenomenological stochastic model for bacterial growth. This model comprises cell division and the linear growth of cells, where growth rates an…
Phase Diagram of Collective Motion of Bacterial Cells in a Shallow Circular Pool
Jun-ichi Wakita, Shota Tsukamoto, Ken Yamamoto +2
The collective motion of bacterial cells in a shallow circular pool is systematically studied using the bacterial species . The ratio of cell length to pool di…
Degree distribution of position-dependent ball-passing networks in football games
Takuma Narizuka, Ken Yamamoto, Yoshihiro Yamazaki
We propose a simple stochastic model describing the position-dependent ball-passing network in football games. In this network, a player on a certain area in the divided fields is…
A simple view of the heavy-tailed sales distributions and application to the box-office grosses of U.S. movies
Ken Yamamoto
This letter treats of the power-law distribution of the sales of items. We propose a simple stochastic model which expresses a selling process of an item. This model produces a sta…
Structure and modeling of the network of two-Chinese-character compound words in the Japanese language
Ken Yamamoto, Yoshihiro Yamazaki
This paper proposes a numerical model of the network of two-Chinese-character compound words (two-character network, for short). In this network, a Chinese character is a node and…
Statistical properties of position-dependent ball-passing networks in football games
Takuma Narizuka, Ken Yamamoto, Yoshihiro Yamazaki
Statistical properties of position-dependent ball-passing networks in real football games are examined. We find that the networks have the small-world property, and their degree di…
Fractal patterns related to dividing coins
Ken Yamamoto
The present paper formulates and solves a problem of dividing coins. The basic form of the problem seeks the set of the possible ways of dividing coins of face values 1,2,4,8,... b…
Hypergeometric solution to a gambler's ruin problem with a nonzero halting probability
Ken Yamamoto
This paper treats of a kind of a gambler's ruin problem, which seeks the probability that a random walker first hits the origin at a certain time. In addition to a usual random wal…
A solvable model of fracture with power-law distribution of fragment sizes
Ken Yamamoto, Yoshihiro Yamazaki
The present paper describes a stochastic model of fracture, whose fragment size distribution can be calculated analytically as a power-law-like distribution. The model is basically…
Fractal behind smart shopping
Ken Yamamoto, Yoshihiro Yamazaki
The 'minimal' payment - a payment method which minimizes the number of coins in a purse - is presented. We focus on a time series of change given back to a shopper repeating the mi…
Topological self-similarity on the random binary-tree model
Ken Yamamoto, Yoshihiro Yamazaki
Asymptotic analysis on some statistical properties of the random binary-tree model is developed. We quantify a hierarchical structure of branching patterns based on the Horton-Stra…
Numerical Approach to Central Limit Theorem for Bifurcation Ratio of Random Binary Tree
Ken Yamamoto, Yoshihiro Yamazaki
A central limit theorem for binary tree is numerically examined. Two types of central limit theorem for higher-order branches are formulated. A topological structure of a binary tr…
Network of two-Chinese-character compound words in Japanese language
Ken Yamamoto, Yoshihiro Yamazaki
Some statistical properties of a network of two-Chinese-character compound words in Japanese language are reported. In this network, a node represents a Chinese character and an ed…