6.2 Frames 
Frames (Minsky, 1979; Rich, 1983; Harmon et al., 1985) 
are used for representation of both concepts as well as 
instances. The aspects of an instance or a concept are 
described with a set of slots. These slots may be filled by 
other frames describing different aspects. An inheritance 
mechanism is integrated in the frame description of a 
concept. That is, more concrete concepts summarize their 
own slots and those of the concepts at higher levels. This 
inheritance economizes redundancy in defining concepts. 
In case of more concrete concepts only some specific 
declarations are needed. The inheritance is realized by the 
slot generalization. This relation generalization and the 
relation necessary part along with their inversions repre- 
sent hierarchies of the net. Fig. 5 shows the hierarchy with 
regard to the relation necessary part. 
A simplified definition of the concept for a coniferous tree 
is presented in Fig. 6. The corresponding ideal shape of the 
coniferous tree is shown in Fig. 7. 
  
CONCEPT Coniferous Tree 
Generalization value: {Tree} 
Necessary Parts value: (T, D1, D2, D3, D4, D5) 
Structure Relations value: {SR1, SR2, SR3, SR4, SR5} 
Attributes value: {Position, Size} 
CF value: [(sr1 & sr2 & sr3 &sr4 & sr5) 
ifTrue: [cf = 100] 
ifFalse: [cf = 0]] 
arguments: {(SR1), (SR2), (SR3), 
(SR4), (SR5)} 
CF-Threshold value: 99 
T value: {Inverted V} 
restriction: nil 
D1 value: (Dot) 
restriction: [10 « diameter « 12] 
D2 value: (Dot) 
restricton: [8 < diameter < 10] 
D3 value: {Dot} 
restriction: [6 < diameter < 8] 
D4 value: {Dot} 
restriction: [4 < diameter < 6] 
D5 value: {Dot} 
restriction: [2 < diameter < 4] 
SR1 value: [Procedure S1] 
arguments: ((T Position), (D1 Position)) 
SR2 value: [Procedure S2] 
arguments: ((T Position), (D2 Position)) 
SR3 value: [Procedure S3] 
arguments: {(T Position), (D3 Position)} 
SR4 value: [Procedure S4] 
arguments: {(T Position), (D4 Position)} 
SR5 value: [Procedure S5] 
arguments: {(T Position), (D5 Position)} 
Position value: [Procedure Coniferous TreePosition] 
arguments: {(T Position), (D1 Position), (D2 Position), 
(D3 Position), (D4 Position), (D5 Position)} 
Size value: [Procedure Coniferous TreeSize] 
arguments: {(T Size), (D1 Size), (D2 Size), 
(D3 Size), (D4 Size), (D5 Size)} 
  
  
  
Fig. 6: Simplified definition of concept coniferous tree. 
  
A 
e eo e eo 
di d2 d3 d4 d5 
  
  
  
Fig.7: Ideal shape of a coniferous tree. 
For a successful instantiation of the concept coniferous 
tree shown in Fig. 7, an instance (t, d1, d2, d3, d4, d5) of 
the corresponding concept (inverted V and dot) has to be 
available for each part of the tree in a defined topology 
660 
with necessary attributes. For the intensional description, 
the necessary parts (T, D1, D2, D3, D4, D5) are defined in 
the slot necessary parts. The single elements of the list are 
references to further substructures represented by slots. 
Each substructure owns a facette value and a facette re- 
striction. The facette value contains a reference to the 
concept and therefore also to the instances of interest. 
Considering the entry of facette restriction, a subset of 
instances may be determined that is relevant for the instan- 
tiation. Thus, T, D1, D2, D3, D4 and D5 characterize lists 
of relevant instances.The entry of slot structure relations 
defines the structure relations that have to be satisfied for 
a combination of instances (t, d1, d2, d3, d4, d5) to execute 
a successful instantiation. The combination of instances is 
determined from the lists T, D1,..., D5. With regard to the 
example, SR1 defines the necessary topology of t and dl. 
For testing of structure relation SR1, facette value (of slot 
SR1) contains the corresponding procedure S1. The argu- 
ments are determined by the argument list defined by the 
facette arguments. Each element of the list represents a 
relational description. The relational description (T Posi- 
tion) for instance means that the position of t has to be 
transfered to the procedure S1. If a combination of in- 
stances (tk, dm, dn, do, dp, dq) exists, which satisfies the 
structure relations, a valuation using the procedure of 
facette value located in slot cf is executed. The necessary 
arguments are determined analogously to the testing of the 
structure relations. For that, the argument list located in 
the facette arguments of slot cf is used. The instantiation 
is successful, if the result of valuation exceeds the thre- 
shold given by the facette value of slot cf-threshold. Sub- 
sequently, the attribute values are evaluated according to 
the testing of structure relations. The relevant attributes 
are defined by the slot attributes and specified by the slots 
position and size. In case of successful instantiation, an 
instance Ix (i.e. now x instances of the concept coniferous 
tree are existing) will be created and stored in the instance 
base using the data structure shown in Fig. 8. The list of 
instances located in facette value of slot instances will be 
extended by the instance Ix. 
  
INSTANCE /x 
Instance Of value: Coniferous Tree 
Necessary Parts value: ((T tx), (D1 dm), (D2 dn), 
(D3 do), (D4 dp), (DS da)} 
Structure Relations value: {(SR1 true), (SR2 true), (SR3 true), 
(SR4 true), (SR5 true)) 
CF value: 100 
  
  
  
Fig.8: Examplefor an instance Ix of the concept coniferous 
tree. 
The presented mechanism for knowledge representation is 
a simplified description. The following system extensions 
give an idea of the additional features integrated in the 
present system. They are necessary for professional utili- 
zation of map interpretation. 
6.3 Extensions of concept definition 
  
6.3.1 Inclusion of Topological Alternatives — The con- 
cept definition introduced so far allows only an interpreta- 
tion of ideal map scenes. With regard to the topology 
shown in Fig. 7, an instantiation is not possible if dot d3 
is not present. This is contradictory to the flexible and fault 
tolerant human capability of reading and interpreting a 
map. To increase flexibility of analysis, the concept defi- 
nition has been expanded. Using a disjunction of combina- 
tions of instances in the slot necessary parts, topological 
alternatives can be included. The corresponding defini- 
tions located in slots structure relations and cf have also 
to be expanded. Fig. 9 shows the revised concept definition 
  
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