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construction system, etc. Each physical pattern is a symbol, as long as it can be
distinguished from other patterns. For example, different English characters are
different symbols. To operate on symbols relies on comparison among different
symbols, i.e. distinguishing which symbols are the same and which ones are
different. Thus fundamental task and functionality of a physical symbol system is
to identify same characters and distinguish different ones.
In the 1980's, Newell etc. focused on the SOAR system, a symbolic cognitive
architecture for general problem solving, based on the Chunking mechanism for
learning and rule-based memory for representation of operators, search control,
etc.
Minsky took the view of psychics, holding that in daily activities, people
apply plenty of knowledge acquired and collected from previous experiences.
Such knowledge is stored in the brain in a structure similar to frame. Thus, he
proposed the frame knowledge representation structure in the 1970's. In the
1980's, Minsky believed that there is no unified theory for human intelligence. In
the famous topic “Society of Mind” he published in 1985, Minsky pointed out
that the society of mind is a vast society of individually simple agents with
certain thinking capabilities.
1.5.2
Logical School
Logical school, with representative researchers such as John McCarthy and Nils
Nilsson, holds the logical perspective for AI research, i.e. describe the objective
world through formalization. This academic school believes that:
Intelligent machines will have knowledge of their environment.
The most versatile intelligent machines will represent much of their
knowledge about their environment declaratively.
For the most versatile machines, the language in which declarative knowledge
is represented must be at least as expressive as first order predicate calculus.
Logical school focuses on conceptual knowledge representation, model
theoretic semantics, deductive reasoning, etc. in AI research. McCarthy claimed
that everything can be represented with the unified frame of logics, and common
sense reasoning will be difficult without some form of non-monotonic reasoning.
