1. Introduction

This article introduces the phenomenon of word class conversion and its universality in different languages, analyzes the difficulties in defining the phenomenon of word class conversion, the lack of quantitative methods, and the controversy over the relationship between language form types. The article points out the challenges of cross linguistic research, the lack of quantification of the productivity of language transfer, and the inadequacy of quantitative analysis of language types. This study aims to quantitatively explore the relationship between word class conversion and language form types by calculating the correlation between conversion productivity and language form richness, in order to reveal the patterns of conversion phenomena in different language types.

2. Definition and related research on word class conversion in languages of different morphological types

Explored the definition and related research of word class conversion in languages of different morphological types. Isolated languages such as Chinese and Vietnamese have almost no inflectional forms, while inflectional languages such as German and Dutch have rich inflectional forms. The forms of English are complex, with Old English being a inflectional language and Modern English having fewer inflectional forms. Some scholars consider it as an isolated language, but English is not a completely isolated language. The phenomenon of class switching is common in isolated languages, but some scholars believe that it should be referred to as part of speech indeterminacy. Modern Chinese and Vietnamese have clear word classes, which is the basis for word classification. The phenomenon of inflection in inflectional language can be divided into two types: narrow and broad. The inflection in inflectional language can be seen as a word formation behavior at the level of lyrical stem. There are numerous transitional words in English, and their transitional word formation is based on word based homomorphic inflection, which is different from typical inflectional languages. Regarding the relationship between word class conversion productivity and language type, it is generally believed that isolated languages have higher conversion productivity, while Germanic languages have higher conversion productivity than Romance and Slavic languages. But this viewpoint is controversial because previous studies lacked quantitative analysis. This article aims to explore the correlation between the productivity of word class conversion and morphological richness through quantitative research, in order to answer the question of the relationship between word class conversion and language morphological types. The productivity of conversion can be calculated by the proportion of conversion words in the vocabulary, and the richness of form can be calculated by MAMSP.

3. Productivity of cross linguistic word class conversion

The productivity of cross linguistic word class conversion was explored through quantitative research, namely the number and proportion of transitional words in commonly used word lists. The research on word lists based on large balanced corpora, such as COCA in English, ensures the scientific and comparable nature of the word lists. The proportion of conversion words reflects the difficulty of language conversion, which is consistent with the definition of morphological productivity. By comparing the number and proportion of conversion words in different languages, it was found that the productivity of conversion is closely related to the type of language form. The proportion of conversion words in isolated languages is the highest, such as English approaching isolated languages, while the proportion of conversion words in Germanic and Romance languages is 4% to 5%, and Slavic languages such as Czech have the lowest proportion. Statistical analysis shows that there is a significant difference in the conversion productivity between isolated language and inflected language. Chinese and Vietnamese, as isolated languages, have a conversion rate of 10% to 20%. The conversion productivity of English differs significantly from other European languages and is closer to Chinese and Vietnamese. This indicates that in terms of word classes, Indo European languages are not completely opposed to Chinese, but rather have a continuum. The differences in inflectional forms between different languages are quantitative rather than absolute.

4. Cross linguistic richness in form

Explored the essential differences in morphological richness between isolated language and inflected language, and attempted to quantitatively distinguish between these two language types. Greenberg's morpheme/word ratio method has been questioned due to operational issues. In this study, we adopted Abeill é's Moving Average Aggregation Degree (MAMSP) method based on annotated treebank to define morphological richness by the number of word forms in a unit morpheme. The lower the MAMSP value, the closer the language is to an isolated language; The higher the value, the closer it is to the inflectional language. The study used the UD 2.5 dataset to calculate MAMSP values for 23 languages within a 500 character window. The results showed that the morphological richness of isolated languages was generally lower than that of inflected languages, with Chinese and Vietnamese approaching 1. The MAMSP value of English was 1.134, which is between isolated and inflected languages, demonstrating its unique language type characteristics. The MAMSP value of Czech language is 1.242, indicating strong inflexibility. These results generally conform to the qualitative judgments of linguists on the morphological features of various languages, providing a quantitative basis for further exploring the relationship between word class conversion and language types.

5. Correlation between conversion productivity and morphological richness

The correlation between word class conversion productivity and morphological richness was explored through quantitative research. Research has found that there is a moderate negative correlation between conversion productivity and morphological richness, meaning that the higher the conversion productivity, the lower the morphological richness. Through the analysis of Figures 1a and 1b, it can be observed that there are differences in the proportion of inflectional and isolated words in terms of the number of word types and the degree of sliding average aggregation. English exhibits specificity in language types, as it is neither in the typical inflectional language nor in the clustering area of isolated languages. After excluding English, there is a high negative correlation between the productivity and morphological richness of the other seven languages. In addition, the relationship between word order and the productivity and richness of form conversion was discussed, pointing out that isolated languages rely on fixed word order and context to express grammatical relationships, while inflectional languages rely on morphological features. The research results support the 'complexity compromise hypothesis', which suggests a negative correlation between the lexical complexity and syntactic complexity of a language. This indicates that language is a complex adaptive system, and there exists a self-organizing and adaptive dynamic balance relationship between various language elements. Isolated language tends to use fixed word order to represent grammatical relationships, while inflectional language has less strict word order restrictions, and the cognitive load of language users is more used to encode the morphological features of words. The dynamic balance between this form and word order reflects the principle of "labor-saving". This study provides a new perspective for understanding how humans encode language information for effective communication.

6. Conclusion

By calculating the correlation between word class conversion productivity and morphological richness in 8 languages, it was found that the conversion productivity is closely related to language morphological types, with isolated languages having the highest conversion productivity, strongly inflected languages having the lowest, and other languages falling in between the two. The richness of morphology forms a continuous system between isolated and inflected languages, indicating a gradient in language morphology types. There is a negative correlation between conversion productivity and morphological richness, reflecting the trade-off between lexical and syntactic complexity of language, supporting the "complexity trade-off hypothesis". The research findings reveal the dynamic balance of language as an internal element of complex adaptive systems, providing a new perspective for understanding natural language information encoding and effective communication.