Abstract
We begin with reviewing the results of unawareness by Modica and Rustichini (1994,1999), Dekel et al.(1998), and Xiong(2009). From Modica and Rustichini ( 1994) and Dekel et al., they claimed that the standard state space model is not rich enough to capture the idea of unawareness. Xiong construct a non-trivial unawareness operator. Next, we use the story “Holmes and Watson” to interpret the idea of unawareness. The last part of the thesis is to accommodate the unawareness by using standard state space model. We propose four axioms and characterize a non-trivial unawareness operator by these four axioms.