Space and time complexity for infinite time Turing machines

被引:2
|
作者
Carl, Merlin [1 ]
机构
[1] Europa Univ Flensburg, Inst Math Nat Wissensch & Tech Bildung, Abt Math & Ihre Didakt, Flensburg, Germany
关键词
Infinite time turing machine; nfinite time register machine; space complexity; time complexity; ordinal computability; PSPACE; recognizability; set theory; NOT-EQUAL NP;
D O I
10.1093/logcom/exaa025
中图分类号
TP301 [理论、方法];
学科分类号
081202 ;
摘要
We consider notions of space by Winter [21, 22]. We answer several open questions about these notions, among them whether low space complexity implies low time complexity (it does not) and whether one of the equalities P=PSPACE, P+ =PSPACE(+) and P++ =PSPACE(++) holds for ITTMs (all three are false). We also show various separation results between space complexity classes for ITTMs. This considerably expands our earlier observations on the topic in Section 7.2.2 of Carl (2019, Ordinal Computability: An Introduction to Infinitary Machines), which appear here as Lemma 6 up to Corollary 9.
引用
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页码:1239 / 1255
页数:17
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