196,568 research outputs found
Descriptional Complexity Issues Concerning Regular Languages
No full textIn the realm of descriptional complexity, systems are compared on the basis of their size. Here, we consider two formalisms for representing regular languages: constant height pushdown automata and straight line programs for regular expressions. We show that their sizes are polynomially related. Comparing them with the sizes of finite state automata and regular expressions, we obtain optimal exponential and double exponential gaps, i.e., a more concise representation of regular languages
One pebble versus log n bits
No full textWe show that pebble machines (i.e., 2-way nondeterministic Turing machines with one pebble that can be moved onto the input cells) working in sublogarithmic weak space are not able to simulate strong log-space bounded 2-way deterministic Turing machines. We prove this by exhibiting a witness language. Moreover, we provide an optimal lower bound on the product of space and input head reversals for pebble machines accepting nonregular languages
More concise representation of regular languages by automata and regular expressions
No full textWe consider two formalisms for representing regular languages: constant height pushdown automata and straight line programs for regular expressions. We constructively prove that their sizes are polynomially related. Comparing them with the sizes of finite state automata and regular expressions, we obtain optimal exponential and double exponential gaps, i.e., a more concise representation of regular languages
The size-cost of Boolean operations on constant height deterministic pushdown automata
No full textAbstractWe study the size-cost of Boolean operations on constant height deterministic pushdown automata, i.e., on the traditional pushdown automata with a built-in constant limit on the height of the pushdown. We design a simulation showing that a complement can be obtained with a polynomial tradeoff. For intersection and union, we show an exponential simulation, and prove that the exponential blow-up cannot be avoided
Removing nondeterminism in constant height pushdown automata
No full textWe study the descriptional cost of converting constant height nondeterministic pushdown automata into equivalent deterministic devices. We show a double-exponential upper bound for this conversion, together with a super-exponential lower bound
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
First results of a photometric and astrometric study of the globular cluster M 71 (NGC 6838)
No full text
We present the first results of a photometric and astrometric
investigation of stars in the region
of the globular cluster M 71 (NGC 6838). Using wide field
CCD observations we determined B and V magnitudes
of 4450 stars up to a limiting magnitude
of V
≤ 18.5 mag.
Relative proper motions were used to derive membership
probabilities for stars with around the centre
of M 71. Our colour-magnitude diagram
(CMD) of 320 probable cluster members
reaches down to V = 18. A well defined red giant bump
- for the first time seen in M 71 - could be detected in our CMD.
From isochrone fitting we find M 71
metal poorer and older than previously assumed.
Four faint variable stars were confirmed
to be members of M 71. Moreover, we detected 13 blue
stragglers among our cluster members.
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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