Goal-directed semantic tutor

ABSTRACT

An efficient Pascal semantic tutoring system is being built that aims at detecting and correcting semantic errors in Pascal programs after programs have been successfully compiled. In order to determine that an input program is correct (more precisely, the program seems to be correct), we attempt to compare the program against certain properties deemed necessary for a correct program. Basic approaches taken include: A problem description which an input program is intended to solve is converted to several properties called, goals, all of which a correct input program must satisfy. From each goal, plans are established which become the conditioin parts of production rules. The action parts of production rules contain certain effects that reflect consequences of goals so far satisfied by the input test program. The input test program is converted to an equivalent LISP expression that preserves the program semantic with such auxiliary words as BEGIN, END, DO, TO, ELSE, THEN eliminated. The resulting expression is more suitable for comparison against aforementioned plans.Pattern symbols and pattern variables are used to facilitate more flexible and powerful pattern matching. In addition, association lists are used to keep track of variables that are actually used in the input test program.

REFERENCES

• 1: John R. Anderson , Brian J. Reiser, The LISP tutor: it approaches the effectiveness of a human tutor, BYTE, v.10 n.4, p.159-175, April 1985
• 2: Avron Barr , Edward A. Feigenbaum, Handbook of AI, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1986
• 3: Carbonell, J.R.,"AI in CAI: An Artificial Intelligence Approacg to Computer-Assisted Instruction, "IEEE Transaction on Man Machine Systems, Dec 1977,pp.190-202.
• 4: W. L. Johnson , Elliot Soloway, PROUST: an automatic debugger for PASCAL programs, BYTE, v.10 n.4, p.179-190, April 1985
• 5: Rychener Michael D., Production Systems as a Programming Language for Artificial Intelligence Applications computer science Department, Carnegie-Mellon University 1975.
• 6: D. A. Waterman , Frederick Hayes-Roth, Pattern-Directed Inference Systems, Academic Press, Inc., Orlando, FL, 1978
• 7: Donald A. Waterman, A guide to expert systems, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1985
• 8: Wertz,- H., Stereotyped Program Debugging: An aid for Novice Progammers," International Journal of Man-Machine Studies, No. 16, 1982, PP. 379-392.
• 9: Daniel Ming-Jen Wu, Implementation of a program assistant: an inference system approach, 1987

INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.2 Language Classifications

          Nouns: Pascal

Additional Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
      D.2.4 Software/Program Verification
          Subjects: Correctness proofs
      D.2.5 Testing and Debugging
          Subjects: Debugging aids
  D.3 PROGRAMMING LANGUAGES
      D.3.1 Formal Definitions and Theory
          Subjects: Semantics

  H. Information Systems
  H.1 MODELS AND PRINCIPLES
      H.1.2 User/Machine Systems
          Subjects: Human factors

General Terms:
Languages, Reliability, Theory, Verification