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The authors have studied 5 patients with syringocele--or cystic dilatation of the excretory ducts in Cowper's glands--using a 7.5 MHz linear high-definition US probe. The urethra was distended with a saline solution introduced through a small Foley's balloon catheter placed in the navicular fossa. Longitudinal and transverse scans were employed at both the(More)
We establish some general schemes relating the computational complexity of a video game to the presence of certain common elements or mechanics, such as destroyable paths, collectible items, doors opened by keys or activated by buttons or pressure plates, etc. Then we apply such “metatheorems” to several video games published between 1980 and 1998,(More)
The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract We prove NP-hardness results for five of Nintendo's largest video game franchises: Mario, all Legend of Zelda games; all Metroid games; and all Pokémon role-playing games. In addition, we prove PSPACE-completeness of the Donkey(More)
Mastermind is a popular board game released in 1971, where a codemaker chooses a secret pattern of colored pegs, and a codebreaker has to guess it in several trials. After each attempt, the codebreaker gets a response from the codemaker containing some information on the number of correctly guessed pegs. The search space is thus reduced at each turn, and(More)
We study the rendezvous problem for two robots moving in the plane (or on a line). Robots are autonomous, anonymous, oblivious, and carry colored lights that are visible to both. We consider deter-ministic distributed algorithms in which robots do not use distance information, but try to reduce (or increase) their distance by a constant factor, depending on(More)
Consider a set of n = 4 simple autonomous mobile robots (decentralized, asynchronous, no common coordinate system, no identities , no central coordination, no direct communication, no memory of the past, deterministic) initially in distinct locations, moving freely in the plane and able to sense the positions of the other robots. We study the primitive task(More)
We study the impact that persistent memory has on the classical rendezvous problem of two mobile computational entities, called robots, in the plane. It is well known that, without additional assumptions, rendezvous is impossible if the entities are oblivious (i.e., have no persistent memory) even if the system is semi-synchronous (SSynch). It has been(More)
Guarding and searching problems have been of fundamental interest since the early years of Computational Geometry. Both are well-developed areas of research and have been thoroughly studied in planar polygonal settings. In this thesis we tackle the Art Gallery Problem and the Searchlight Scheduling Problem in 3-dimensional polyhedral environments, putting(More)
Robots with lights is a model of autonomous mobile computational entties operating in the plane in Look-Compute-Move cycles: each agent has an externally visible light which can assume colors from a fixed set; the lights are persistent (i.e., the color is not erased at the end of a cycle), but otherwise the agents are oblivious. The investigation of(More)