The tasks are shown in pictures below.
Task stack_ABC -- the Sussman Anomaly: +---+ | A | +---+ +---+ | C | ---------> | B | +---+ +---+ +---+ | A | | B | | C | -----+---+--+---+----- -----+---+----- TABLE Task stack_ABC_2: +---+ | A | +---+ +---+ | A | ---------> | B | +---+ +---+ +---+ | B | | C | | C | -----+---+--+---+----- -----+---+----- TABLE Task stack_CBA: +---+ | C | +---+ +---+ | C | ---------> | B | +---+ +---+ +---+ | A | | B | | A | -----+---+--+---+----- -----+---+----- TABLE Task stack_BAC: +---+ | B | +---+ +---+ | C | ---------> | A | +---+ +---+ +---+ | A | | B | | C | -----+---+--+---+----- -----+---+----- TABLE