MS98-VARIABLE-ORDER : FLAG

MS98-VARIABLE-ORDER is a flag or parameter.
Determines the variable ordering for the unification
graph. Only affects higher-order searches.
Suppose N is the maximum number of unifiers for a
given list of variables, and K is the length of the list.
For values 0--3, the variables are first grouped into lists of duplicate
copies (so each variable is listed with its duplicates, if any)
0 : Sort by N, largest first.
1 : Sort by N, smallest first.
2 : Sort by K, largest first.
3 : Sort by K, smallest first.
10--13 : Group the variables into lists of length 1, and then proceed
as 0--3.
20--23 : Group the variables into lists that occur together (i.e. two
variables go into the same list if their expansion nodes are not separated
by any junctive node in the etree) and then proceed as for 0--3.
30--33 : Group the variables as for 0--3, and then reduce the lists
to length 1 while keeping the variables in the same order.
40--43 : Group the variables as for 20--23, and then reduce the lists
to length 1 while keeping the variables in the same order.
Other values X will behave like (X div 10) for variable grouping and
(X mod 10) for ordering the groups.
MS98-VARIABLE-ORDER takes values of type INTEGER+.
It belongs to subjects MS98-MINOR .
Its default value is 1
Its current value is 1.

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