<s>
Hidden	B-Application
algebra	I-Application
provides	O
a	O
formal	B-Application
semantics	I-Application
for	O
use	O
in	O
the	O
field	O
of	O
software	B-General_Concept
engineering	I-General_Concept
,	O
especially	O
for	O
concurrent	O
distributed	O
object	B-Language
systems	I-Language
.	O
</s>
<s>
Hidden	B-Application
algebra	I-Application
was	O
studied	O
by	O
Joseph	O
Goguen	O
.	O
</s>
<s>
It	O
handles	O
features	O
of	O
large	O
software-based	O
systems	O
,	O
including	O
concurrency	B-Operating_System
,	O
distribution	B-Architecture
,	O
nondeterminism	O
,	O
and	O
local	O
states	O
.	O
</s>
<s>
It	O
also	O
handled	O
object-oriented	B-Language
features	O
like	O
classes	O
,	O
subclasses	O
(	O
inheritance	B-Language
)	O
,	O
attributes	B-General_Concept
,	O
and	O
methods	B-Language
.	O
</s>
<s>
Hidden	B-Application
algebra	I-Application
generalizes	O
process	O
algebra	O
and	O
transition	B-Application
system	I-Application
approaches	O
.	O
</s>
