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.

翻译：我们研究一些使用封闭时间相似曲线(CTCs)的计算变式,这些曲线对计算机的记忆、信息载荷能力和反恐委员会的范围施加了各种限制;我们充分描述多时概率和量子计算机所认可的语言类别,这些语言可以将一个古典的点移到自己的过去;这些狭小的CTs被证明增加了有限的非确定主义对确定性计算机的力量,导致在恒定空间概率和量子计算中加速加速速度。我们表明,由于一台时间机器不断出现负延迟,人们可以在不需要事先知道运行时间的情况下实施基于CTC的计算。