22 research outputs found
On the power of real-time turing machines under varying specifications
We investigate the relative computing power of Turing machines with differences in the number of work tapes, heads pro work tape, instruction repertoire etc. We concentrate on the k-tape, k-head and k-head jump models as well as the 2-way multihead finite automata with and without jumps. Differences in computing power between machines of unlike specifications emerge under the real-time restriction. In particular it is shown that k+1 heads are more powerful than k heads for re
Minimizing Access Pointer into Trees and Arrays
Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / N00014-79-C-0424National Science Foundation / MCS-801070
Relativized obliviousness
Relativized obliviousness is introduced to capture the intuitive idea, that some problems allow fastest computations which are more oblivious than do other problems, without any of such computations being oblivious in the standard sense. It is shown that each increase in the obliviousness of an algorithm (in several different well-defined meanings), for the solution of some problems, may necessarily require an increase in computation time from T(n) steps to T(n) log T(n) steps. There is, however, no problem for which a total oblivious algorithm requires more than order T(n) log T(n) steps, if the best algorithm for it runs in T(n) steps. We use on-line Turing machines as model of computation
Optimal Dynamic Embedding of Trees into Arrays
Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / N00014-79-C-042