Djab: I have the feeling that there is a mistake in one of the solutions claimed "correct":
R4S4R5Q6S5S3S1P4T2R6 and then, I think the correct move to make a second eye in the corner is T4 and not R1
Indeed, after R1, the opponent can answer S2 which prevents the eye in the corner and win the race at S6
I have the feeling that there is a mistake in one of the solutions claimed "correct": R4 S4 R5 Q6 S5 S3 S1 P4 T2 R6 and then, I think the correct move to make a second eye in the corner is T4 and not R1 Indeed, after R1, the opponent can answer S2 which prevents the eye in the corner and win the race at S6