The paper constructs a hedge algebra and its extension with fuzzy logic to represent the quantitative aspect of trust/distrust and that of their cognitive factors. Then these two aspects are combined to estimate the degree of trust/distrust based on the degree of their cognitive factors. | Journal of Computer Science and Cybernetics, , (2015), 203– 213 DOI: COMBINATION OF FORMAL LOGIC AND HEDGE ALGEBRA TO ESTIMATE THE DEGREE OF TRUST NGUYEN MANH HUNG1,2 1 Posts and Telecommunications Institute of Technology (PTIT), Hanoi, Vietnam 2 UMI UMMISCO 209 (IRD/UPMC), Hanoi, Vietnam nmhufng@, mhnguyen@ Abstract. Trust plays a more and more important role in many fields of computer sciences such as ambient intelligence, interaction human - machine, affective computing, etc. This paper firstly constructs a logical framework to represent the qualitative aspect of trust/distrust based on a logic of belief, a logic of time, and dynamic logic. Secondly, the paper constructs a hedge algebra and its extension with fuzzy logic to represent the quantitative aspect of trust/distrust and that of their cognitive factors. Then these two aspects are combined to estimate the degree of trust/distrust based on the degree of their cognitive factors. Keywords. Modal logic, hedge algebra, fuzzy logic, trust, distrust 1. INTRODUCTION Trust plays a more and more important role in many fields of computer sciences such as ambient intelligence, interaction human - machine, affective computing, etc. In this paper, an approach is introduced to combine the qualitative and the quantitative aspects of trust/distrust. At the qualitative cognitive level, some emotions based on the cognitive definition of trust [3] and distrust [4] are represented in a formal logic based on the logic of beliefs and choices as the one of Herzig and Longin [12] (a refinement from Cohen and Levesque [7]), the logic of time (introduced by Arthur Prior [18]), and dynamic logic introduced by Fischer and Ladner [8] and Harel et al. [11]. This part is closed to the work of Goudou et al. [10, 16], Bonnefon et al. [1, 2], and Nguyen [17]. At the quantitative level, the qualitative aspects of trust/distrust are represented by introducing a hedge algebra to .
