Proposition Variable(命题变元) Usually,we use lower case letters to denote proposition variables (e.g.,p,q,r) ·p:Today is Friday ·q:2+2=4 ·r:Bill is from Boston ·The range of a proposition variable:{T,月 p:Today is Friday(p=F) ·q:2+2=4(q=T) r:Bill is from Boston (r=F)Proposition Variable（命题变元） • Usually, we use lower case letters to denote proposition variables (e.g., p, q, r) • p : Today is Friday • q : 2+2=4 • r : Bill is from Boston • The range of a proposition variable: {T, F} • p: Today is Friday (p=F) • q: 2+2=4 (q =T) • r: Bill is from Boston (r=F)