factor    APS  solved    CHA  solved   both
    1.00   4817  153/154   2997   40/45   7814
    1.25   2806  153/154   2752   40/45   5558
    1.50   2806  153/154   2889   40/45   5695
    2.00   2806  153/154   3220   40/45   6026   <- the text's choice
    3.00   2806  153/154   3756   40/45   6562
    4.00   2806  153/154   4006   40/45   6812
  credit   3568  153/154   3020   40/45   6588   <- no multiplier, bound = bisection + 1 step

      C0    APS    CHA   both  promise
    0.10   5344   3051   8395  bisection + 1 step(s)
    0.50   4656   3002   7658  bisection + 1 step(s)
    1.00   3568   3020   6588  bisection + 1 step(s)
    2.00   3692   2712   6404  bisection + 2 step(s)
    5.00   3006   2615   5621  bisection + 5 step(s)