The complexity of loop programs
ACM '67 Proceedings of the 1967 22nd national conference
Computation: finite and infinite machines
Computation: finite and infinite machines
Algebraic Structures with Hard Equivalence and Minimization Problems
Journal of the ACM (JACM)
Decidable problems for powerful programs
Journal of the ACM (JACM)
The Complexity of the Equivalence Problem for Simple Programs
Journal of the ACM (JACM)
On the fundamental limitations of transformational design
ACM Transactions on Design Automation of Electronic Systems (TODAES)
Analysis of simple programs over different sets of primitives
POPL '80 Proceedings of the 7th ACM SIGPLAN-SIGACT symposium on Principles of programming languages
Linear programs in a simple reversible language
Theoretical Computer Science
Dichotomization, reachability, and the forbidden subgraph problem(Extended Abstract)
STOC '76 Proceedings of the eighth annual ACM symposium on Theory of computing
Decision problems in computational models
Proceedings of ACM conference on Proving assertions about programs
A note on comparison of subrecursive hierarchies
Information Processing Letters
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Many problems, some of them quite meaningful, have been proved to be recursively unsolvable for programs in general. The paper is directed toward a class of programs where many decision problems are solvable. The equivalence problem has been proved to be unsolvable for the class L2 of loop programs defining the class of elementary functions. A solution is given for the class L1 defining the class of simple functions. Further, a set of other decision problems not directly connected with the equivalence problem is investigated. These problems are found again to be unsolvable for the class L2; but as before, a solution is given for the class L1. It is concluded, therefore, that there is a barrier of unsolvability between the classes L1 and L2.