(Plesniewicz, 2014). These languages have 
semantics based on formal concepts. 
A formal concept has the following components: 
  The name C of the concept; 
  The unverse U
C
 of the concept – a countable 
set of names denoting possble instances of the 
concept. The universe also contains so-called 
surrogates {object-oriented identifyiers):  
Surr = {#1, #2,…} ⊆U
C
. 
  The extension E
C
 of the concept, i.e., the set of 
names that denoteinstances  of the concept, 
E
C
⊆ U
C
; 
  The  coreferentiality  relation  ~
C  
⊆ E
C
X  E
C
.
Ifa  ~
C 
b  then the names a  and b denote the 
same object of the application modelled. 
Example 1. Define a formal concept as follows: 
  U
Person 
=String ∪ 
     {[Surr:x,Name:y,SSN:z,works_in:u]| 
y ∈String,  z ∈typeSSN,  x, u ∈Surr}; 
Here  typeSSN  is the attribute domain (data 
type) for social security numbers (i.e., strings 
of the format XXX-XX-XXXX, where X are 
decimal digits); 
  E
Person
= {…,#105,[Surr:#110, 
Name:john,SSN:078-05-1120, 
works_in:#27],…}; 
  {…,#105~
Person
[Surr:#105, 
Name:john,SSN:078-05-1120, 
works_in:#27],…}. 
The concept Person has three attributes: 
Name,SSN and works_in. The first two attributes 
take values in the standard data type String and in 
the specified data type typeSSN.The third attribute 
takes the value #27  which is the surrogate 
referred to some organization where John works. 
The conceptPersonfrom Example 1 is static in 
the sense that their extensions do not depend on 
time. In general, the extension of a concept is 
variable. It is natural to introduce a special attribute 
Por(point of reference) whose values refer to this 
variability.The attribute Por may have such 
components as time (point or interval), position in 
space, state of affairs, context, truth degree et al. 
For any point of reference γ, we denote by E
C
γ
 
the extension of the concept C  at the point of 
reference γ. Let Γ be the set of all possible points of 
reference that are considered under a given 
conceptualization. Then we say that the family of 
sets {E
C
γ
 | γ ∈ Γ} is thetotal extension of the concept 
C, 
So, formally conceptualization of a given 
application can be represented by a (finite) set S of 
formal concepts with the same set Γ of points of 
reference. An ontology  Othat specifies the set S of 
formal concepts is written in the concept languages 
of the system BMK. 
The sentences of the ontology O  differ in what 
components of concepts they specify. The sentences 
that specify concept universes U
C
(C ∈ S), define the 
structure of members of U
C
, and therefore, we call 
them  structural  sentences. We call logical  the 
sentences that specify the extensions E
C 
(C ∈ S). We 
also call transitory the sentences that specify the 
changes (E
C
γ
– E
C
δ
)  ∪ (E
C
δ
– E
C
γ
) in the transition 
from the point γ to the point δ. 
In the system “Binary Model of Knowledge”, 
there are the languages for structural, logical and 
transitory specification of ontologies. 
2.1  Language LSS of Structural 
Specification 
In the language LLS two type of concepts are 
distinguished:  classes  and  binary relations.  LLS 
sentences are composed of primitive sentences that 
have the following forms: 
C[D], C[A:D], C[A:T], (CLD), (CLD)[E], 
(CLD)[A:E], (CLD)[A:T]. 
Here C, D, Eare names of classes, L is a name of 
binary relation, A is an attribute, and T is a data type 
specification. (There are some means for defining 
data types in LSS.) 
An arbitrary structural sentence is obtained by 
joining primitive sentences. For example, the 
sentence C[D,  A: (String, Integer), E(*)]arises from 
the primitive sentencesC[D], C[A: (String, Integer)] 
and C[D, A:E(*)]. 
Here are some examples of structural sentences. 
1)  Car[Brand:String,Engine, 
    Dimensions: 
(Length/m/:Integer, 
Width/mm/:Integer, 
Height/mm/:Integer,
 
Wheelbase/mm/:Integer) 
Gearbox:String]. 
2)  Engine[Type:Integer, 
Power/hp/:Integer, 
Max_speed/km/h/: Integer]. 
3)(Person owns Car} 
[RegisterDate:Date, 
DocsReg:String]. 
The assertion e ∈ E
C
γ
 corresponds to the fact      
“e  is an instance of the concept C at the point of 
reference  γ”, and e  ∉E
C
γ
 corresponds to the fact      
KEOD 2020 - 12th International Conference on Knowledge Engineering and Ontology Development