Information Technology Reference
In-Depth Information
assertions, they declare the relation of individual constant and concept, i.e. the
relation of element and set. Semantics of concept assertion can be interpreted as
follows:
·
I
(
u
)
u
պ
C
(
a
) iff
a
∈
C
;
I
(
u
)
u
պ
¬
C
.
For example, under certain state, individual constant a denotes a block, and
this means individual constant a belongs to the concept of block, and it is denoted
as Block(a); individual constant b is a button, and it is denoted as Button(b).
Role assertions declare the relation of two individual objects or the attribute
of individual object. It is a binary relation, and its semantics can be explained as
the following:
·
·
(
a
) iff
a
∉
C
I
(
u
)
u
պ
R
(
a
1
,
a
2
) iff (
a
1
,
a
2
)∈
R
;
I
(
u
)
u
պ
¬
R
.
For example, under certain state, agent a1 and agent a
2
are acquaintance, and
it is denoted as
·
(
a
1
,
a
2
) iff (
a
1
,
a
2
)∉
R
hasAquaintance(a
1
, a
2
)
, Object a presses on object b, and it is
denoted as
. Role assertions may also declare some attributes of
individual object. For example, Button b
1
is in o pen state, and it is denoted as
hasState(b
1
, O
N
)
On(a, b)
hasLength(a,
10).
Analogously, for a particular state u, those formulas that are composed of
assertion formulas can be interpreted as follows, where
ϕ
and
are assertion
formulas:
·
; the length of object a is 10,and it is denoted as
u
պ
¬
ϕ
iff
u
տϕ
;
·
u
պϕӼɂ
iff
u
պϕ
and
u
պɂ
;
Action execution results in change of world state, so action also may be
defined as a state transition relationship. But the process of action change is the
process of individual attribute change or individual relation change in fact, so
under certain state, all individual attribute, relation description and so on consists
of the world state description. These individual attribute, relation descriptions
may be defined based on action description (Definition 2.33). State in DDL
corresponds to all condition interpretation of action description under
corresponding state in fact, so action may be interpreted based on
aforementioned condition interpretation and description logic interpretation.
·
u
պ
ϕ
→
ɂ
iff
u
պϕ
¼
u
պɂ
.
