Almost everyone in China knows this story, even elementary school pupils: Once upon a time, there was a weapon salesman claiming with confidence to one crowd that all his spears were capable of piercing every shield that existed in the world, then he turned around and told the other crowd mysteriously that all his shields were not penetrable. A bystander who heard both claims asked him, “How ab...

Birds can rely on a variety of cues for orientation during migration and homing. Celestial rotation provides the key information for the development of a functioning star and/or sun compass. This celestial compass seems to be the primary reference for calibrating the other orientation systems including the magnetic compass. Thus, detection of the celestial rotational axis is crucial for bird or...

The atmospherical pressure gradients of spherical celestial bodies are very important in astrophysics and other related areas. The classical form of the gradient in a gravitation-dominated celestial body: dp dR = − R ρ has been widely adopted for quit a long time. But, in this form, a factor has been neglected: the centrifugal force that due to the thermal motion of gaseous particles in a centr...

Stellar dynamics shares these equations with celestial mechanics (a term which is used here to denote the study of the orbital dynamics of bodies in the solar system), but there are important differences of emphasis. In stellar dynamics all masses are comparable, whereas in celestial mechanics one mass tends to dominate (either the sun or a primary). This has an effect on the methods used and t...

Association rule mining, in which generating frequent patterns is a key step, is an effective way of identifying inherent and unknown interrelationships between characteristics of celestial spectra data and its physicochemical properties. In this study, we first make use of the first-order predicate logic to represent knowledge derived from celestial spectra data. Next, we propose a concept of ...

A language L ⊆ A∗ is literally idempotent in case that uav ∈ L if and only if uav ∈ L for each u, v ∈ A∗, a ∈ A. Such classes result naturally by taking all literally idempotent languages in a classical (positive) variety or by considering a certain closure operator. We initiate their systematic study. Various classes of such languages can be characterized using syntactic methods. A starting ex...

Hamlet: Has this fellow no feelings of his business, that he sings at grave-making? Horatio: Custom hath made it in him a property of easiness. (Hamlet Act V, scene i) Hamlet is appalled by the gravedigger's insensitivity towards death and corpses. Horatio explains that the gravedigger is so accustomed to such things that he no longer shares Hamlet's seriousness. We contend that human dissectio...