for POS being non empty ParOrtStr holds
( POS is OrtAfPl-like iff ( ex a, b being Element of POS st a <> b & ( for a, b, c, d, p, q, r, s being Element of POS holds
( a,b // b,a & a,b // c,c & ( a,b // p,q & a,b // r,s & not p,q // r,s implies a = b ) & ( a,b // a,c implies b,a // b,c ) & ex x being Element of POS st
( a,b // c,x & a,c // b,x ) & not for x, y, z being Element of POS holds x,y // x,z & ex x being Element of POS st
( a,b // c,x & c <> x ) & ( a,b // b,d & b <> a implies ex x being Element of POS st
( c,b // b,x & c,a // d,x ) ) & ( a,b _|_ a,b implies a = b ) & a,b _|_ c,c & ( a,b _|_ c,d implies ( a,b _|_ d,c & c,d _|_ a,b ) ) & ( a,b _|_ p,q & a,b // r,s & not p,q _|_ r,s implies a = b ) & ( a,b _|_ p,q & a,b _|_ r,s & not p,q // r,s implies a = b ) & ex x being Element of POS st
( a,b _|_ c,x & c <> x ) & ( not a,b // c,d implies ex x being Element of POS st
( a,b // a,x & c,d // c,x ) ) ) ) ) )