An audit of a banking transactions system has found that on an earlier occasion, two
joint holders of account \( A \) attempted simultaneous transfers of Rs. 10000 each from
account \( A \) to account \( B \). Both transactions read the same value, Rs. 11000, as the
initial balance in \( A \) and were allowed to go through. \( B \) was credited Rs. 10000 twice.
\( A \) was debited only once and ended up with a balance of Rs. 1000.
Which of the following properties is/are certain to have been violated by the
system?
