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Nevertheless, it is too general to realize generalization by means of
transformation from constant to variable, and the rule may fail in some special
cases.
9.4 Explanation Generalization using Global Substitutions
DeJong and Mooney proposed Explanation Generalization using Global
Substitutions (abbreviated as EGGS) (DeJong & Mooney, 1986) in 1986. In EBG,
through goal concept regression of instance explanation structure, the disjunction
is left out to realize generalization. The EGGS explains construction unit
constructors and connects these units when explanation can be unified.
The robot planning STRIPS(Fikes, Hart and Nilsson, 1972) was the first to
realize generalization explanation. It is a macro command system, which
constructs and generalizes robot planning. When the goal is given, STRIPS
executes search process, finds out a sequence of operators and transforms a given
initial world model status into goal status. The initial model and goal are as
follows:
Initial world model
INROOM(ROBOT,R1)
INROOM(BOX1,R2)
CONNECTS(D1,R1,R2)
CONNECTS(D1,R2,R3)
BOX (BOX1)
┆
(
∀
x, y, z) [CONNECTS(x, y, z)
¼
CONNECTS(x, z, y)]
The goal formula:
(
∃
x)[BOX(x)
∧
INROOM(x, R1)]
The operators STRIPS adopted is as follows
GOTHRU(d,r
1
,r
2
)
Precondition:INROOM(ROBOT,r1)
∧
CONNECTS(d,r1,r2)
Delete list:INROOM(ROBOT,r1)
Add listINROOM(ROBOT,r2)
PUSHTHRU (b, d, r
1
, r
2
)
Precondition:INROOM(ROBOT,r
1
)
∧
CONNECTS(D,r
1
,r
2
)
∧
INROOM(b,r
1
)
Delete list:INROOM(ROBOT,r
1
) INROOM(b,r
1
)
Add list:INROOM(ROBOT,r
2
) INROOM(b,r
2
)
