STOC

It is known that k tapes are no better than two tapes for nondeterministic machines. We show here that two tapes are better than one. In fact, we show that two pushdown stores are better than one tape. Also, k tapes are no better than two for ...

Let k be a constant ≥ 2, and let us consider only deterministic k-tape Turing machines.

We assume t₂(n) > n and t₂ is computable in time t₂. Then there is a language which is accepted in time t₂, but not accepted in any time t₁ with t₁(n) = o(t₂(n)).

...

The results of this paper concern the question of how fast machines with one type of storage media can simulate machines with a different type of storage media. Most work on this question has focused on the question of how fast one deterministic machine ...

Each multicounter machine can be simulated in real-time by an oblivious one-head tape unit.

This paper introduces a two-dimensional alternating Turing machine (2-ATM) which is an extension of an alternating Turing machine to two-dimensions. This paper also introduces a three-way two-dimensional alternating Turing machine (TR2-ATM) which is an ...

The purpose of automata theory is to study and classify those properties of words that may be defined by a finite structure, say a finite automaton or a finite monoid. It seems natural to consider the same problem for infinite words. This amounts to ...

In 1969 Rabin introduced tree automata and proved one of the deepest decidability results. If you worked on decision problems you did most probably use Rabin's result. But did you make your way through Rabin's cumbersome proof with its induction on ...

Several methods for testing VLSI chips can be classified as signature methods. Both conventional and signature testing methods apply a number of test patterns to the inputs of the circuit. The difference is that a conventional method examines each ...

Many researchers have proposed that ensembles of processing elements be organized as trees. This paper explores how large tree machines may be assembled efficiently from smaller components. A principal constraint that we consider is the limited number ...

In this paper, we introduce a new framework within which to study VLSI layout problems. The framework is based on a straightforward generalization of the Lipton-Tarjan notion of a planar separator and, unlike previous approaches, leads to universally ...

Energy conservation is a key question in today' s society and the proliferation of VLSI circuits encourages an energy conscious approach to their design. Although a single chip at current densities may consume less than one watt of power, assembling ...

Storage media such as digital optical disks, PROMS, or paper tape consist of a number of “write-once” bit positions (wits); each wit initially contains a “0” that may later be irreversibly overwritten with a “I”. We demonstrate that such “write-once ...

In this article, we study an alternate approach that shifts the records among adjacent pages rather than using overflow pointers when space is needed for inserting a record in a sequential file. We show how to use this method to achieve a worst-case ...

We present a new representation for linked lists. This representation allows one to efficiently insert objects into the list and to quickly determine the order of list elements. The basic data structure, called an indexed 2-3 tree, allows one to do n ...

In this paper, we raise and investigate the question of (storage) space- (retrieval) time tradeoff for a static database, in the general framework of Fredman's. As will be seen, such tradeoff results also lead to lower bounds on the complexity of ...

Two complexity measures for query languages are proposed. Data complexity is the complexity of evaluating a query in the language as a function of the size of the database, and expression complexity is the complexity of evaluating a query in the ...

Query languages for relational databases have received considerable attention. In 1972 Codd [Cod72] showed that two natural mathematical languages for queries—one algebraic and the other a version of first order predicate calculus—had identical powers ...

A general framework for the denotational treatment of concurrency is introduced. The key idea is the notion of process which is element of a domain obtained as solution of a domain equation in the style as considered previously by Plotkin. We use tools ...

We consider the complexity of satisfiability and determination of truth in a particular finite structure for different propositional linear temporal logics. We show that both the above problems are NP-complete for the logic with F operator and are ...

In this paper we consider the Computation Tree Logic (CTL) proposed in [CE] which extends the Unified Branching Time Logic (UB) of [BMP] by adding an until operator. We establish that CTL has the small property by showing that any satisfiable CTL ...

A logic, Pr(DL), is presented, which enables reasoning about probabilistic programs or, alternatively, reasoning probabilistically about conventional programs. The syntax of Pr(DL) derives from Pratt's first-order dynamic logic and the semantics extends ...

In this paper we prove several results concerning this complexity measure. First we establish (in a non-constructive manner) that there exist languages which cannot be recognized with less than n communication (obviously, communication n is always ...

This paper introduces a class of 1 player games of perfect information, which we call complementing games;; the player is allowed moves which complement the value of successive plays. A complementing game is symmetric if all noncomplement moves are ...

This paper studies two aspects of the power of space-bounded probabilistic Turing machines. Section 2 presents a simple alternative proof of Simon's recent result [13] that space-bounded probabilistic complexity classes are closed under complement. ...

We give two counterexamples to the random oracle hypothesis as formalized by Bennett and Gill[2]. We then discuss the future of the random oracle hypothesis in light of these examples We believe that these examples will severely test any new candidate ...

We prove that a parallel RAM with no write conflicts allowed requires Ω(log n) steps to compute the Boolean or of n bits stored in the first n global memory cells. We first argue that this result is subtler than it appears, and in fact the “obvious” ...

This work generalizes decision trees in order to model algorithms which allow probabilistic, nondeterministic, or alternating control. Two geometric techniques for proving lower bounds on the time required by ordinary decision trees (Dobkin and Lipton's ...

For a property π on graphs, the corresponding edge-deletion problem P_ED(π) (edge-contraction problem P_EC(π), resp.) is defined as follows: Given a graph G, find a set of edges of minimum cardinality whose deletion (contraction, resp.) results in a graph ...

Many important combinatorial optimization problems, including the traveling salesman problem (TSP), the clique problem and many others, call for the optimization of a linear functional over some discrete set of vectors.

Given an arbitrary but fixed integer r ≥ 3. We show that testing r-variate polynomials with integer coefficients for irreducibility is m-reducible in polynomial time of the total degree and the largest coefficient length to testing bivariate polynomials ...