## 2 Literature Review
### Research Gap  
During the literature review, certain gaps were identified. These gaps arise from the specificity of this research, which has not been given much attention in practice so far. First, there is a lack of research focusing on the selection of suppliers of agricultural equipment and machinery in the Agriculture 4.0 system. In the seven papers mentioned above, it could be seen that no attention was paid to suppliers within the Agriculture 4.0 system. A similar situation is found in other studies where the focus was on the implementation of this system and not on the importance of suppliers in this system. This research opens up the possibility of developing research directly focused on the selection of suppliers of agricultural equipment and machinery in the Agriculture 4.0 system, which gives a strategic dimension to improving agricultural production. The procurement of equipment and machinery is a long-term investment for agricultural producers, so it is necessary to use a reliable supplier. Second, although the IFS approach is widely used in the agricultural sector, especially in the agricultural supply chain, it is not used enough in practice with a concrete example of supplier selection in this agricultural system. Applying this approach opens up the possibility of including uncertainty and insecurity in the selection of suppliers. Although this has been used in many previous studies, this study will offer a simplification of this approach, which will open up the possibility of improving this decision-making approach. In addition, Bonferroni mean operators are used, which allow for better alignment of DM ratings in supplier selection. Third, previous research has used the selection of sustainable suppliers in agriculture. This research seeks to build on this approach by incorporating sustainability principles into the selection of equipment and machinery suppliers. The specificity of this selection is that suppliers, in addition to supplying equipment and machinery, also offer additional services in terms of training farmers to use new technologies and providing certain support in doing so. Nevertheless, introducing these dimensions into the research model is key to the development of sustainable agricultural production. Sustainability must be present in all processes in the supply chain in order to achieve sustainable agricultural production. Fourth, it is necessary to improve the decision-making system in practice and to incorporate the dimensions of uncertainty and insecurity into the decision-making process. In this way, this process will be improved and contribute to making a more comprehensive decision Therefore, it is necessary to develop flexible models adapted to the agricultural sector in order to improve decision-making in agriculture. This is especially present in situations where subjective assessments of DMs are present that are subject to influence. Therefore, subjective opinion carries a certain amount of uncertainty, and it is necessary to develop flexible and robust models in agriculture so that the decision is realistic and correct in order to avoid risks in investment decision-making.