使用窄CTC进行计算
Computation with narrow CTCs
摘要：
我们研究了封闭类时曲线（CTC）的计算的一些变体，其中对计算机的内存施加了各种限制，以及CTC的信息承载能力和范围。我们充分刻画了语言类的多项式时间概率和量子计算机，可以发送一个单一的经典位自己的过去。这种狭窄的CTC被证明可以为确定性计算机增加有限非确定性的能力，并导致常数空间概率和量子计算的指数加速。我们表明，给定一个恒定的负延迟的时间机器，可以实现CTC为基础的计算，而不需要事先知道的运行时间。
英文摘要：
We examine some variants of computation with closed timelike curves (CTCs), where various restrictions are imposed on the memory of the computer, and the information carrying capacity and range of the CTC. We give full characterizations of the classes of languages recognized by polynomial time probabilistic and quantum computers that can send a single classical bit to their own past. Such narrow CTCs are demonstrated to add the power of limited nondeterminism to deterministic computers, and lead to exponential speedup in constant-space probabilistic and quantum computation. We show that, given a time machine with constant negative delay, one can implement CTC-based computations without the need to know about the runtime beforehand.
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