| ∀ str, r, st, st0. validfieldlist(str, r, sks0, st) ∧ st ⊆ st0 → validfieldlist(str, r, sks0, st0), validfieldlist(str, r, sk + sks0, st), st ⊆ st0 ⊦ validfieldlist(str, r, sk + sks0, st0) |
st ⊆ st0, validfieldlist(str, r, sk ' + sks0, st), ∀ str, r, st, st0. validfieldlist(str, r, sks0, st) ∧ st ⊆ st0 → validfieldlist(str, r, sks0, st0) ⊦ validfieldlist(str, r, sk ' + sks0, st0)
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ sk + sks = sk ' + sks])]]