1,117 research outputs found
The mechanism of double exponential growth in hyper-inflation
Analyzing historical data of price indices we find an extraordinary growth
phenomenon in several examples of hyper-inflation in which price changes are
approximated nicely by double-exponential functions of time. In order to
explain such behavior we introduce the general coarse-graining technique in
physics, the Monte Carlo renormalization group method, to the price dynamics.
Starting from a microscopic stochastic equation describing dealers' actions in
open markets we obtain a macroscopic noiseless equation of price consistent
with the observation. The effect of auto-catalytic shortening of characteristic
time caused by mob psychology is shown to be responsible for the
double-exponential behavior.Comment: 9 pages, 5 figures and 2 tables, submitted to Physica
The Grounds For Time Dependent Market Potentials From Dealers' Dynamics
We apply the potential force estimation method to artificial time series of
market price produced by a deterministic dealer model. We find that dealers'
feedback of linear prediction of market price based on the latest mean price
changes plays the central role in the market's potential force. When markets
are dominated by dealers with positive feedback the resulting potential force
is repulsive, while the effect of negative feedback enhances the attractive
potential force.Comment: 9 pages, 3 figures, proceedings of APFA
Precise calculation of a bond percolation transition and survival rates of nodes in a complex network
<p><b>(a) Cumulative distributions of the survival rate at the critical point (<i>f</i><sub>c</sub> = 0.994) of nodes belonging to the largest shell, <i>k</i><sub><i>s</i></sub> = 25, in the initial state. (b) Schematic figure of calculating the survival rate</b>. Each link is supposed to be removed with the same probability and we compare the sizes of separated clusters. The gray nodes belong to the largest cluster. <b>(c) Cumulative distribution of link numbers at the critical point in a log-log plot</b>. The solid line is calculated only in the largest cluster, and a superposition of 100 trials. The dotted line is calculated for all clusters, and we take superposition of 10 trials. The guide line shows the slope of 1.5, the same slope as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0119979#pone.0119979.g001" target="_blank">Fig 1(a)</a>.</p
Random walker in a temporally deforming higher-order potential forces observed in financial crisis
Basic peculiarities of market price fluctuations are known to be well
described by a recently developed random walk model in a temporally deforming
quadric potential force whose center is given by a moving average of past price
traces [Physica A 370, pp91-97, 2006]. By analyzing high-frequency financial
time series of exceptional events such as bubbles and crashes, we confirm the
appearance of nonlinear potential force in the markets. We show statistical
significance of its existence by applying the information criterion. This new
time series analysis is expected to be applied widely for detecting a
non-stationary symptom in random phenomena.Comment: 5 pages, 13 figure
Self-organization of structures and networks from merging and small-scale fluctuations
We discuss merging-and-creation as a self-organizing process for scale-free
topologies in networks. Three power-law classes characterized by the power-law
exponents 3/2, 2 and 5/2 are identified and the process is generalized to
networks. In the network context the merging can be viewed as a consequence of
optimization related to more efficient signaling.Comment: Physica A: Statistical Mechanics and its Applications, In Pres
Assembling real networks from synthetic and unstructured subsets: the corporate reporting case
The analysis of interfirm business transaction networks provides invaluable insight into the trading dynamics and economic structure of countries. However, there is a general scarcity of data available recording real, accurate and extensive information for these types of networks. As a result, and in common with other types of network studies - such as protein interactions for instance - research tends to rely on partial and incomplete datasets, i.e. subsets, with less certain conclusions. Hereh, we make use of unstructured financial and corporate reporting data in Japan as the base source to construct a financial reporting network, which is then compared and contrasted to the wider real business transaction network. The comparative analysis between these two rich datasets - the proxy, partially derived network and the real, complete network at macro as well as local structural levels - provides an enhanced understanding of the non trivial relationships between partial sampled subsets and fully formed networks. Furthermore, we present an elemental agent based pruning algorithm that reconciles and preserves key structural differences between these two networks, which may serve as an embryonic generic framework of potentially wider use to network research, enabling enhanced extrapolation of conclusions from partial data or subsets
Nonequilibrium Phase Transitions in Models of Aggregation, Adsorption, and Dissociation
We study nonequilibrium phase transitions in a mass-aggregation model which
allows for diffusion, aggregation on contact, dissociation, adsorption and
desorption of unit masses. We analyse two limits explicitly. In the first case
mass is locally conserved whereas in the second case local conservation is
violated. In both cases the system undergoes a dynamical phase transition in
all dimensions. In the first case, the steady state mass distribution decays
exponentially for large mass in one phase, and develops an infinite aggregate
in addition to a power-law mass decay in the other phase. In the second case,
the transition is similar except that the infinite aggregate is missing.Comment: Major revision of tex
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