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- Turlough Neary, Damien Woods
- MCU
- 2007

We present small polynomial time universal Turing machines with state-symbol pairs of (5, 5), (6, 4), (9, 3) and (18, 2). These machines simulate our new variant of tag system, the bi-tag system and are the smallest known universal Turing machines with 5, 4, 3 and 2-symbols respectively. Our 5-symbol machine uses the same number of instructions (22) as the… (More)

- Turlough Neary, Damien Woods
- FCT
- 2009

We give small universal Turing machines with state-symbol pairs of (6, 2), (3, 3) and (2, 4). These machines are weakly universal, which means that they have an infinitely repeated word to the left of their input and another to the right. They simulate Rule 110 and are currently the smallest known weakly universal Turing machines. Despite their small size… (More)

- Turlough Neary, Damien Woods
- ICALP
- 2006

We show that the problem of predicting t steps of the 1D cellular automaton Rule 110 is P-complete. The result is found by showing that Rule 110 simulates deterministic Turing machines in polynomial time. As a corollary we find that the small universal Turing machines of Mathew Cook run in polynomial time, this is an exponential improvement on their… (More)

- Turlough Neary, Damien Woods
- Theor. Comput. Sci.
- 2006

We present a number of time-efficient small universal Turing machines. We show that there exists deterministic polynomial time universal Turing machines with state-symbol products of (3, 11), (5, 7), (6, 6), (7, 5) and (8, 4). These machines are the smallest known universal Turing machines that simulate TMs in polynomial time.

We present new small polynomial time universal Turing machines with state-symbol pairs of (9, 3) and (18, 2). These machines simulate our new variant of tag system, the bi-tag system and are the smallest known universal Turing machines with 3-symbols and 2-symbols respectively.

- Damien Woods, Turlough Neary
- CiE
- 2007

- Turlough Neary, Damien Woods
- SOFSEM
- 2009

We survey some work concerned with small universal Turing machines, cellular automata, tag systems, and other simple models of computation. For example it has been an open question for some time as to whether the smallest known universal Turing machines of Minsky, Rogozhin, Baiocchi and Kudlek are efficient (polynomial time) simulators of Turing machines.… (More)

- J W Brown, C T Kesler, T Neary, L M Fishman
- Hormone and metabolic research = Hormon- und…
- 2001

We tested the effects of 17beta-estradiol as well as its catechol- and methoxy-derivatives, two androgens (DHEA and testosterone), a glucocorticoid (cortisol), a mineralocorticoid (aldosterone), and progesterone on the activity of ERK(1,2), a key component of the ERK/MAPK enzyme phosphorylation cascade, in SW-13 human adrenal carcinoma cells. After a… (More)

- Damien Woods, Turlough Neary
- 2006 47th Annual IEEE Symposium on Foundations of…
- 2006

We show that 2-tag systems efficiently simulate Turing machines. As a corollary we find that the small universal Turing machines of Rogozhin, Minsky and others simulate Turing machines in polynomial time. This is an exponential improvement on the previously known simulation time overhead and improves a forty year old result in the area of small universal… (More)

- Damien Woods, Turlough Neary
- MCU
- 2007

We present three small universal Turing machines that have 3 states and 7 symbols, 4 states and 5 symbols, and 2 states and 13 symbols, respectively. These machines are semi-weakly universal which means that on one side of the input they have an infinitely repeated word, and on the other side there is the usual infinitely repeated blank symbol. This work… (More)