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- Lvzhou Li, Daowen Qiu
- Theor. Comput. Sci.
- 2008

Two quantum finite automata are equivalent if for any input string x the two automata accept x with equal probability. In this paper, we focus on determining the equivalence for 1-way quantum finite automata with control language (CL-1QFAs) defined by Bertoni et al and measure-many 1-way quantum finite automata (MM-1QFAs) introduced by Kondacs and Watrous.… (More)

- Daowen Qiu, Lvzhou Li, Xiangfu Zou, Paulo Mateus, Jozef Gruska
- Acta Inf.
- 2011

Multi-letter quantum finite automata (QFAs) are quantum variants of the one-way multi-head finite automata (J. Hromkovič, Acta Informatica 19 (1983) 377-384). It has been shown that this new one-way QFAs (multi-letter QFAs) can accept with no error some regular languages, for example (a + b) * b, that are not acceptable by QFAs of Moore and Crutchfield [20]… (More)

- Shenggen Zheng, Daowen Qiu, Lvzhou Li
- Theor. Comput. Sci.
- 2013

Two-way quantum automata with quantum and classical states (2QCFA) were introduced by Ambainis and Watrous in 2002. In this paper we study state succinctness of 2QCFA. For any m ∈ Z + and any < 1/2, we show that: 1. there is a promise problem A eq (m) which can be solved by a 2QCFA with one-sided error in a polynomial expected running time with a constant… (More)

- Lvzhou Li, Daowen Qiu, Xiangfu Zou, Lvjun Li, Lihua Wu, Paulo Mateus
- Theor. Comput. Sci.
- 2012

Generally, unitary transformations limit the computational power of quantum finite au-tomata (QFA). In this paper we study a generalized model named one-way general quantum finite automata (1gQFA), in which each symbol in the input alphabet induces a trace-preserving quantum operation, instead of a unitary transformation. Two different kinds of 1gQFA will… (More)

- Lvzhou Li, Daowen Qiu
- Theor. Comput. Sci.
- 2006

- Lvzhou Li, Daowen Qiu
- Theor. Comput. Sci.
- 2009

- Shenggen Zheng, Daowen Qiu, Lvzhou Li
- Int. J. Found. Comput. Sci.
- 2002

We introduce 2-way finite automata with quantum and classical states (2qcfa's). This is a variant on the 2-way quantum finite automata (2qfa) model which may be simpler to implement than unrestricted 2qfa's; the internal state of a 2qcfa may include a quantum part that may be in a (mixed) quantum state, but the tape head position is required to be… (More)

- Daowen Qiu, Lvzhou Li, Paulo Mateus, Amílcar Sernadas
- J. Comput. Syst. Sci.
- 2015

We show that there are quantum devices that accept all regular languages and that are exponentially more concise than deterministic finite automata (DFA). For this purpose , we introduce a new computing model of one-way quantum finite automata (1QFA), namely, one-way quantum finite automata together with classical states (1QFAC), which extends naturally… (More)

- Daowen Qiu, Lvzhou Li
- Frontiers of Computer Science in China
- 2008

- Paulo Mateus, Daowen Qiu, Lvzhou Li
- Inf. Comput.
- 2012

Several types of automata, such as probabilistic and quantum automata, require to work with real and complex numbers. For such automata the acceptance of an input is quantified with a probability. There are plenty of results in the literature addressing the complexity of checking the equivalence of these automata, that is, checking whether two automata… (More)