| 1 | 10. ( < M @ N,x.concl > ) < ( < M @ (  x.N),concl > ) 
( L:Sequent List.
s L.( (s) = 0)
& ( s L.|= s  |= < M @ N,x.concl > )
& ( a:Assignment. s L.a | s  a | < M @ N,x.concl > )) L:Sequent List.
s L.( (s) = 0)
& ( s L.|= s  |= < M @ (  x.N),concl > )
& ( a:Assignment. s L.a | s  a | < M @ (  x.N),concl > ) |