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The archaeological zone of Izapa was an important pre-Hispanic settlement of probable Mixe-Zoque affiliation in the Soconusco region, southeast of the current state of Chiapas, whose occupational sequence extended from the Early Preclassic (1800 BC) to the Early Postclassic (1200 AD). Throughout its long habitation, various population movements occurred within the settlement. During the Classic period, in the complex known as Group F, of which only 2.88 ha are currently protected, monumental structures were built that integrated a civic-ritual compound. Previous research identified a prolonged constructive sequence, specifically in the main pyramid (Structure 125-A). To identify possible construction moments prior to those currently appreciated and determine the state of conservation of some of its monumental structures, a geophysical survey was carried out by means of georadar and electrical resistivity tomography techniques in various areas of Group F. Through these, it was possible to detect several anomalies that can be interpreted as archaeological structures, including platforms, channels and walls. Some of these elements were verified by archaeological excavations. The different depths at which these possible structures are located speak of a prolonged occupation of Group F, with various modifications to its architectural configuration. [ABSTRACT FROM AUTHOR]

The chemical characterization of materials recovered from archaeological sites has been used to relate artifacts to their respective sources of raw material. For this, conventional methods of classical statistics are commonly used, such as bivariate graphs, cluster analysis and linear data transformations. Those who have applied these methods claim to have a high degree of confidence in the correct assignment of materials to their respective sources. However, if empirical data deviate from theoretical assumptions, classical statistical techniques can produce incorrect assignments. In this paper, we propose a semi-supervised learning procedure using clustering and classification based on models of mixtures of multivariate asymmetric exponential power distributions. The objective is to trace the origin and provenance of obsidian archaeological materials from the archaeological zone of Izapa, Chiapas, significantly optimizing the result of the correct allocation of unlabeled data by employing only limited supervision in the form of labeled instances. The effectiveness of the proposed method was evaluated by a controlled experiment using data from a set of geological samples from obsidian deposits. Subsequently, the method was applied to analyze a set of obsidian artifacts collected in excavations within Izapa dated for the Classic period. In both cases, well-defined classifications were obtained that, in the case of Izapa, allowed to determine the consumption of materials from Guatemalan sources, as well as some relationship with sources from western and central Mexico. [ABSTRACT FROM AUTHOR]

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