Maestro n° 103 : Page 7 - Gr 4
r4c4 =9=7= r4c4 -7- r7c4 =7=5= r7c4 -5- r7c6 =5= r6c6 -5-3- r6c6 =3= r6c5 -3- r3c5 =3=9= r3c5 -9- r4c5 =9=7= r4c5 => r4c4 ≠ 7 and r4c5 ≠ 9