let n1, n2, n3, n4 be Element of NAT ; :: thesis: for S being Gene-Set
for p1, p2 being Individual of S holds crossover p1,p2,n1,n2,n3,n4 is Individual of S
let S be Gene-Set; :: thesis: for p1, p2 being Individual of S holds crossover p1,p2,n1,n2,n3,n4 is Individual of S
let p1, p2 be Individual of S; :: thesis: crossover p1,p2,n1,n2,n3,n4 is Individual of S
reconsider q1 = crossover p1,p2,n1,n2,n3, q2 = crossover p2,p1,n1,n2,n3 as Individual of S ;
crossover q1,q2,n4 is Individual of S ;
hence crossover p1,p2,n1,n2,n3,n4 is Individual of S ; :: thesis: verum