Exploitation of Flexibility in Sequential Networks - The Unknown Component Problem: Theory and Applications - page 222

and after dcmin we would see:
print_stats_aut planetxs-dcmin.aut
"csf": complete, deterministic, progressive, and
Moore.
13 inputs (13 FSM inputs) 13 states (12 accepting) 61
trans
Inputs = {v0,v1,v2,v3,v4,v5,v6,v11,v12,v7,v8,v9,v10}
Thus dcmin has resulted in using don't cares to state minimize from 49 states to
12 accepting states by creating immediately equivalent states.
We note that it is possible to execute the latch split procedure as follows:
read_blif_mv planet.blif
latch_expose
latch_split 0-3
source planetS.script
dcmin planetxs.aut planet-dcmin.aut
but this would expose all latches, and would force the outputs of X to be aligned
with the states of S. This would overly constrain the solution. If this is tried on the
example, the final solution planet-dcmin.aut would have 3 more states than
obtained by exposing only v11 and v12 . Also, in checking the particular original
solution planeta.blif , we note that it has 16 states, all of which are deter-
ministic, and cannot be state minimized, whereas planetxs-dcmin has only 12
states, which may be nondeterministic in the outputs. Finally print stats aut
certifies that the underlying automaton is deterministic.

14.4 Minimizing the Communication Lines

When synthesizing the components of a synchronous composition of FSMs, it may
be of interest to minimize the number of communication lines of a given component.
For instance, in the network of Fig. 14.2 we may wish to replace the FSM M A j with
a component that depends on a single input variable, instead of two input variables,
if at all possible.
In order to capture all the FSMs which can replace a given component FSM M A j
(defined over the input alphabets I Df I 1 ;:::;I j

l g and the output alphabets O D
f O 1 ;:::;O r g ), without changing the external behavior of the initial composition,
we solve the equation M X M Context Š M A j M Context ,whereM Context
describes the joint behavior of all other component FSMs or of an appropriate
neighbour FSM (window approach). Say that the equation is solved over the set
f I 1 ;:::;I l ;O 1 ;:::;O r g of alphabets of the component FSM M A j . We would
like to check whether there exists a proper subset P f I 1 ;:::;I l g of input
alphabets of M A j such that a solution of the equation exists over the subset P of
input alphabets and the set of output alphabets of M A j .