Let us consider that the input vector of simultaneous consensus always belongs to an x-legal
condition C, such that x
The algorithm described in Fig. 12.8 is a simple adaptation of the early deciding conditionbased consensus algorithm described in Fig. 11.9, in which the processes decide during the
round (t + 1 − x). This adaptation consists in the suppression of line 9 (because x
line 14 (to obtain simultaneous decision during the last round).
Figure 12.8: A condition-based simultaneous consensus algorithm (code for pi)
Modify this algorithm so that the processes early decide during the round (t + 1 − max(D, x)).
Hints.
• Round r, 1 ≤ r ≤ t + 1 − x, is a simple merge of round r of the algorithms described
in Fig. 12.3 and Fig. 12.8. The message broadcast by a process pi at round r now has to
piggyback four values, namely, v condi, vtmfi, esti, and fi[r − 1].
• In the merge of both algorithms, line 10 of the algorithm described in Fig. 12.3, and
lines 15-17 the algorithm described in Fig. 12.8 must be replaced by the statement if
(r = bhi[r]) ∨ (r = t + 1 − x) then ... end if.
Solution in [301, 367].