Extended Abstract
Introduction
Urban morphology as an organized knowledge and attention to the diverse forces involved in the formation of a city, politics and ideology as a process, and geographical space as a form and context; are always interrelated with each other. Therefore, the decision-making ability, implementation and position of political elites in the social hierarchy and their ideology and the laws and policies they establish; are very decisive in creating spatial changes. An examination of the morphological structure of Tabriz city shows that this city, as the political center of the province, lacked oil, but the political-economic structure of the city is dependent on the central government with income sources from oil, and this political-economic system has had an impact on the structure of planning and implementation of urban development programs. Because, the political economy dependent on oil creates rent, and this factor will create many developments and problems. Therefore, the present study, with a critical-analytical approach, seeks to examine the impact of the state-centered economy on urban morphology developments in the production of space and physical management of the city and to explain the role of each of the influential factors in this field.
 
Methodology
present article, with a descriptive-analytical method, seeks to explain the role of the organization and social-management institutions on urban morphology developments with an emphasis on the political economy governing the management of the city of Tabriz. The statistical population includes the residents of the city of Tabriz. Given the specialization of the subject and the complexity of the analysis techniques and questionnaire, the community of experts in the form of a Delphi panel was used. In this regard, the snowball sampling method was used with a specialized panel of 30 people with specialties related to the research topic in the field of urban planning. The research indicators are also based on the components of urban morphology changes in the form of 5 main components (selected by the statistical community of experts in four Delphi stages). The validity of the questionnaire was confirmed by 10 urban planning experts. Reliability was also estimated at 0.854 according to the Cronbach's alpha formula. Factor analysis tests and structural equation modeling with SmartPLS3 software and finally the multi-subject-multi-actor model with Mactor software were used to analyze the data.
 
Results and discussion
According to the research findings with the structural equation model, the highest impact of actors is related to the physical structure with an impact coefficient of 0.681 and a significance level of 0.000 and also to the management structure with a coefficient of 0.646 and a significance level of 0.000. These results indicate that the actors of the morphological changes of Tabriz city under the management of a centralized and state economy have been able to create profound changes in the urban structure of Tabriz through physical components, including the quality of housing (strength, area, design and architecture), the proportionality of public uses with urban needs, and urban transportation and traffic. In addition, the variance coefficient of 0.903 shows that the model in question has well explained the causal relationships between variable and hidden structures. According to the actor matrix, the position of the actors and drivers in the morphological changes of Tabriz city is divided into four parts. As a result, given that in the process of morphological changes of Tabriz city, the role of citizens has not been given much attention and the participation of this group has been weak due to the management of the ruling political economy based on the state economy. Therefore, they have been identified as a dependent group in the actor matrix. Also, the indicators of "landscape and beauty of natural landscapes around the city; proportionality of transportation costs and accessibility; The quality of the city's public infrastructure; and the level of participation of different groups" are in the defeated sector. Finally, the last output of the model shows how the actors and activists of the morphological transformation process of Tabriz city under the management of a centralized and state economy, under mutual relations, affect each other's behavior and actions to achieve their goals. The output of this model shows that the role of the municipality in this field is very colorful and has a direct and very strong relationship with the Road and Urban Development Department and housing cooperative companies and the private sector (real estate consultants and build-sell companies). In contrast, the relationship with local institutions and citizens is not very acceptable. This is while citizens and their needs should be at
 
the center of the spatial communication of the actors. And the Road and Urban Development Department as the custodian of the plans and the municipality as the custodian of the plans should have a strong and reciprocal relationship with the citizens. Consulting engineering companies, as another arm of the implementation of urban programs and projects, also have a marginal and advisory role and do not have much relationship with management institutions, and mainly have an intermediate and intermediate role.
 
Conclusion
The study of the role of actors in the morphological changes of Tabriz city showed that the Road and Urban Development Department and the municipality have the most role in the urban morphological changes. And citizens, as the main users and beneficiaries of urban changes, have a subordinate and dependent role in this process. Also, the triangle of relations between the municipality-road and urban development-private and cooperative sectors through appropriate correlation coefficient indicators at the city level; land and housing prices in proportion to the location of the neighborhood and facilities and access; street layout and urban skeleton in accordance with traffic needs, have been able to play a dominant role in urban morphological changes.