Tria Francesca, Loreto Vittorio, Servedio Vito D P
Physics Department, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
Sony Computer Science Laboratories, 6, rue Amyot, 75005 Paris, France.
Entropy (Basel). 2018 Sep 30;20(10):752. doi: 10.3390/e20100752.
Zipf's, Heaps' and Taylor's laws are ubiquitous in many different systems where innovation processes are at play. Together, they represent a compelling set of stylized facts regarding the overall statistics, the innovation rate and the scaling of fluctuations for systems as diverse as written texts and cities, ecological systems and stock markets. Many modeling schemes have been proposed in literature to explain those laws, but only recently a modeling framework has been introduced that accounts for the emergence of those laws without deducing the emergence of one of the laws from the others or without ad hoc assumptions. This modeling framework is based on the concept of adjacent possible space and its key feature of being dynamically restructured while its boundaries get explored, i.e., conditional to the occurrence of novel events. Here, we illustrate this approach and show how this simple modeling framework, instantiated through a modified Pólya's urn model, is able to reproduce Zipf's, Heaps' and Taylor's laws within a unique self-consistent scheme. In addition, the same modeling scheme embraces other less common evolutionary laws (Hoppe's model and Dirichlet processes) as particular cases.
齐普夫定律、希普斯定律和泰勒定律在许多存在创新过程的不同系统中普遍存在。它们共同代表了一组引人注目的典型事实,涉及诸如书面文本与城市、生态系统与股票市场等多样系统的总体统计、创新率以及波动的标度。文献中已提出许多建模方案来解释这些定律,但直到最近才引入了一个建模框架,该框架能够解释这些定律的出现,而无需从其他定律推导其中一条定律的出现,也无需特设假设。这个建模框架基于相邻可能空间的概念及其关键特征,即在探索其边界时(即取决于新事件的发生)会动态重构。在此,我们阐述这种方法,并展示这个通过修改后的波利亚瓮模型实例化的简单建模框架如何能够在一个独特的自洽方案中重现齐普夫定律、希普斯定律和泰勒定律。此外,相同的建模方案还涵盖其他不太常见的演化定律(霍普模型和狄利克雷过程)作为特殊情况。