2,579 research outputs found
Mastermind is NP-Complete
In this paper we show that the Mastermind Satisfiability Problem (MSP) is
NP-complete. The Mastermind is a popular game which can be turned into a
logical puzzle called Mastermind Satisfiability Problem in a similar spirit to
the Minesweeper puzzle. By proving that MSP is NP-complete, we reveal its
intrinsic computational property that makes it challenging and interesting.
This serves as an addition to our knowledge about a host of other puzzles, such
as Minesweeper, Mah-Jongg, and the 15-puzzle
Separation-Sensitive Collision Detection for Convex Objects
We develop a class of new kinetic data structures for collision detection
between moving convex polytopes; the performance of these structures is
sensitive to the separation of the polytopes during their motion. For two
convex polygons in the plane, let be the maximum diameter of the polygons,
and let be the minimum distance between them during their motion. Our
separation certificate changes times when the relative motion of
the two polygons is a translation along a straight line or convex curve,
for translation along an algebraic trajectory, and for
algebraic rigid motion (translation and rotation). Each certificate update is
performed in time. Variants of these data structures are also
shown that exhibit \emph{hysteresis}---after a separation certificate fails,
the new certificate cannot fail again until the objects have moved by some
constant fraction of their current separation. We can then bound the number of
events by the combinatorial size of a certain cover of the motion path by
balls.Comment: 10 pages, 8 figures; to appear in Proc. 10th Annual ACM-SIAM
Symposium on Discrete Algorithms, 1999; see also
http://www.uiuc.edu/ph/www/jeffe/pubs/kollide.html ; v2 replaces submission
with camera-ready versio
Synthesis of 1-substituted 3-amino-1H-1,2,4-triazoles from ethyl N-(5-phenyl-1,2,4-oxadiazol-3-yl)formimidate
A general and efficient method for the synthesis of 1-substituted 3-amino-1H-1,2,4-triazoles has been developed. The desired 3-amino-1H-1,2,4-triazoles (3) were prepared in good to excellent yields from ethyl N-(5-phenyl-1,2,4-oxadiazol-3-yl)formimidate (1a) and anilines or amines (2) via a one-pot process involving formimidamide formation followed by a thermal monocyclic rearrangement. The benzoyl protecting group could be readily removed by sulfuric acid promoted deprotection
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