两个脑袋总比两盘磁带好
Two heads are better than two tapes
摘要：
我们证明了具有两个单头一维磁带的图灵机不能识别集合{x2 x '|x \in {0，1}^*，x'是x}的前缀，尽管它可以用三个磁带、两个二维磁带或一个双头磁带来这样做，或者用一个磁带在线性时间内这样做。特别是，这解决了长期以来的猜想，即如果两个头的图灵机的头在同一个一维磁带上，而不是在不同的一维磁带上，那么它可以实时的识别更多的语言。
英文摘要：
We show that a Turing machine with two single-head one-dimensional tapes cannot recognize the set {x2x'| x \in {0,1}^* and x' is a prefix of x} in real time, although it can do so with three tapes, two two-dimensional tapes, or one two-head tape, or in linear time with just one tape. In particular, this settles the longstanding conjecture that a two-head Turing machine can recognize more languages in real time if its heads are on the same one-dimensional tape than if they are on separate one-dimensional tapes.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
