I guess the program corrects for the varying stretches of time between the exact event times (when estimating the conditional probability of event occurrence). What were the 5 event times?

Thank you for the answer and suggestion, The Event times are listed in the first column of the screenshot.

0.663

1.002

1.582

2.396

2.486

I will try to dig deeper into estimation process. I thought these values are the same as the actual survival probability.

As the risk set drops from 11 to 9 (ie 1 observation has left the risk set without an event), the numbers are correct:

0.598 = [1 - 1/13]. [1 - 1/12] . [1 - 1/11] . [1 - 1/9] . [1 - 1/8]