- λR. â\88\80b,f,L1,K1. â¬\87*[b,f] L1 ≘ K1 →
- â\88\80K2,T. K1 ⪤*[R,T] K2 â\86\92 â\88\80U. â¬\86*[f] T ≘ U →
- â\88\83â\88\83L2. L1 ⪤*[R,U] L2 & â¬\87*[b,f] L2 ≘ K2 & L1 ≡[f] L2.
+ λR. â\88\80b,f,L1,K1. â\87©*[b,f] L1 ≘ K1 →
+ â\88\80K2,T. K1 ⪤*[R,T] K2 â\86\92 â\88\80U. â\87§*[f] T ≘ U →
+ â\88\83â\88\83L2. L1 ⪤*[R,U] L2 & â\87©*[b,f] L2 ≘ K2 & L1 ≡[f] L2.