1 Research Background

This section introduces the background of research on language complexity, noting that the equi-complexity hypothesis once held a significant position but has been challenged in recent years, emphasizing that language complexity varies with language contact, time, and sociocultural changes. It also discusses the impact of translation, as an important form of language contact, on language complexity, and how the introduction of information theory has made the measurement of complexity possible. Finally, it outlines the purpose of this paper, which is to study the complexity characteristics of noun phrases in translated Chinese and their diachronic changes based on a diachronic corpus of three translations of *The Wealth of Nations*.

2 Literature Review

This section provides a comprehensive review of the current state of research on the syntactic complexity and noun phrase complexity of translated Chinese. In terms of syntactic complexity, it points out that translated Chinese exhibits more complex structures and richer hierarchies compared to original Chinese, reflected in the frequency of special sentence patterns, average sentence length, and word length. However, further exploration is needed in measuring syntactic complexity regarding diversity at the lexical and structural levels and functional classification at the phrase level. Regarding noun phrase complexity, it emphasizes that translated Chinese noun phrases are influenced by both the English source language and original Chinese, making them more complex than original Chinese. However, existing studies are mostly based on literary corpora, and the applicability of non-literary materials, as well as micro-measurement indicators, require further expansion. This study, based on three translations of *The Wealth of Nations*, aims to investigate the characteristics and diachronic changes of noun phrase complexity at the formal, structural, and cognitive levels to enrich the diachronic research perspective.

3 Research Design

This section details the research design, including data sources, the definition and measurement methods of noun phrase complexity, and data processing procedures. The data come from a self-built diachronic corpus of three Chinese translations of *The Wealth of Nations*, translated by Guo Dali and Wang Yanan (1931), Zhou Xianwen and Zhang Hanyu (1964), and Yang Jingnian (1998), respectively. Noun phrase complexity is measured from three dimensions: formal, structural, and cognitive. Formal complexity focuses on length, modifier position, and diversity; structural complexity is related to dependency tree height; and cognitive complexity relies on dependency distance. In terms of data processing, Stanford Parser 4.0 is used for automatic syntactic annotation, and Python programming is employed to extract noun phrases, followed by complexity level classification and analysis of the extracted noun phrases.

4 Research Findings

This section examines the complexity characteristics of noun phrases in translated Chinese across the three translations of *The Wealth of Nations*. In terms of formal complexity, attributives are the main cause of complexity, with modifier positions showing diversity and exhibiting post-positional phenomena, influenced by both original Chinese and the English source language. The richer the modifiers, the higher the complexity. Structural complexity is examined through dependency tree height, where nested dependencies increase, and the use of functional dependencies affects the degree of nesting, indicating a higher degree of grammaticalization in translated Chinese. Cognitive complexity is related to dependency distance, with the average dependency distance of translated Chinese noun phrases falling between modern Chinese and English, indicating that cognitive complexity is higher than that of the English source language but lower than that of original Chinese.

4.2 Diachronic Changes in Noun Phrase Complexity

By analyzing the noun phrase complexity in the three translations of *The Wealth of Nations*, this section explores its diachronic changes. The study finds that formal complexity is related to time, with the frequency of complex forms changing inconsistently across translations, showing an initial increase followed by a decrease, while the frequency of simple forms shows a declining trend. This indicates that the inherent rules of Chinese constrain translated Chinese, with the external influence of the English source language interacting with the conventional forces of Chinese. From the perspective of modifier parts of speech, the increase in complex forms is mainly due to the addition of verb modifiers, while the growth of simple forms is primarily driven by an increase in adjective and adverb modifiers. From the perspective of dependency relations, the increase in complex forms is mainly reflected in the addition of attributive clause modifiers, while the growth of simple forms is seen in the increase of compound word modifiers. In terms of structural complexity, as time progresses, functional dependencies in noun phrases increase, particularly case dependencies, indicating an increase in structural complexity and a higher degree of grammaticalization. In terms of cognitive complexity, the average dependency distance of noun phrases in the three translations shows an upward trend, indicating an increase in cognitive complexity.

5 Conclusion

This section summarizes the impact of differences in form and structure between English and Chinese noun phrases on the diachronic increase in the complexity of translated Chinese noun phrases. It points out that the elliptical nature of traditional Chinese grammar and the integration of English grammar in translation have led to refined logical cohesion, grammatical structures, and the emergence of redundancy. Based on the self-built corpus of three translations of *The Wealth of Nations*, the study analyzes the diachronic characteristics and changes in the complexity of translated Chinese noun phrases from formal, structural, and cognitive perspectives. It finds that translated Chinese integrates features of both the English source language and original Chinese, with overall noun phrase complexity showing an upward trend, though specific manifestations vary, providing evidence for the Europeanization of Chinese. At the same time, certain increases in complexity may imply a decrease in cognitive complexity. The study only analyzed non-literary materials, and future research needs to further examine materials from other genres and the interconnections and interactions of related indicators.