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After closing, the multi-period portfolio can be corrected and revised at regular intervals. The philosophy behind using multi-period portfolio models is that investors often have a multi-period view of future changes in assets, which can be the result of technical and fundamental analysis or statistical model analysis. In conventional multi-period portfolio models, it is assumed that the forecast and correction time horizons are the same for all assets. However, one asset may be forecasted over a one-month horizon while another may be forecasted over a two-month horizon, and both may be revised in the future. The purpose of this study is to present a multi-period portfolio model in which assets have different time horizons for corrections or an asset may not be traded for the first few periods and then enter the correction stage. In this model, fuzzy variables defined in a credibility space are used to describe the return, and the credibility measure controls the risk. The model's objective function is to maximize the portfolio's ultimate wealth, and a constraint is used to control portfolio risk, in which the validity of the portfolio's ultimate wealth below a certain threshold is controlled at a certain level of confidence. A combination of particle swarm optimization and simulation is used to find the best solution. Finally, using a numerical example, the model is implemented on a portfolio with 6 assets and 4 monthly time steps on the Tehran Stock Exchange.

One of the main concerns in educational settings has been the degree of the learners’ involvement in learning and the extent to which they actively participate in classroom talks and interactions. The present study is an emic-based ethnographic study aimed at providing insights about patterns of talk and different degrees of interaction in EFL university classes with a specific focus on teacher’s role. To this end, three different classes were observed for twelve consecutive sessions. Students were both male and female senior EFL students at Najafabad Azad University. The age of the participants ranged between 22 and 28. These classes were taught by the same instructor so that the researcher was directly involved in observing participants’ interactions in the targeted classrooms and in the data collection procedures. The participants’ oral behavior was carefully observed and recorded. To guarantee higher validity, some participants were also interviewed. The results of data analysis revealed that male and female students showed different degrees of contribution to classroom interactions. However, the students’ degree of involvement in the classroom discussions were linked to the related schemata, type of activity, and learners’ interest in the conversation topic rather than interactants’ gender. In addition, most of the involvements were teacher-initiated and directed. Notably, the findings can be of considerable value to teachers’ professional development and can highlight the importance and the value of using specific strategies that can be introduced and employed by the teacher to increase the degree of the students’ involvement in classroom interactions as well as motivate them to take responsibility of their own learning.