-theorem drops_trans: â\88\80L,L2,s,des2. â\87©*[s, des2] L â\89¡ L2 â\86\92 â\88\80L1,des1. â\87©*[s, des1] L1 ≡ L →
- â\87©*[s, des2 @@ des1] L1 ≡ L2.
+theorem drops_trans: â\88\80L,L2,s,des2. â¬\87*[s, des2] L â\89¡ L2 â\86\92 â\88\80L1,des1. â¬\87*[s, des1] L1 ≡ L →
+ â¬\87*[s, des2 @@ des1] L1 ≡ L2.