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I argue that no new gismu are needed and that {carna} can be
used as is. I wrote a description of how I use carna, with a picture as an attachment. I hope it explains my point of view (no pun intended) well enough. Open the picture before reading this or it will be impossible to follow. The vector ML stands orthogonally on the plane defined by the points on circle c. Both MA and MB are on this plane. A body (object) is placed on the plane such that ML is its axis of rotation. The vector ML has an orientation/face, which serves as the viewpoint from which the direction of the rotation is determined. It always faces point A, the starting point of any rotation. To indicate the direction of rotation, another point on the circle must be chosen and the shortest way to it is the direction, here this point would be B. The starting orientation, that is, the original point A that is chosen, is not significant. The direction only depends on the polarity of the axis vector ML. All the above can be visualised by either a human hand or by imagining yourself being the axis vector, your head being at point L with your body facing the imaginary line AL'. The second point B is either to the left or to the right of point A and it is this point B that determines whether the body rotates clockwise or counter-clockwise. Because we can refer to this point B by using relative terms like "left" and "right", we don't have to know where this point lies in order to know whether or not we're moving clockwise. Thus, since all we need to define the direction is an axis ML, which has an inherent orientation as mentioned above, and a point B *relative* to our starting orientation towards AL', {carna}, which has both these as x2 and x3 respectively is plenty to express clockwise and counter-clockwise motion. carna2 will not need to be specified for bodies that overlap almost completely with the axis ML, like for instance a standing human being, and for objects like a disk that's lying flat on the plane, we only need to choose the polarity of vector ML. It is arguable whether or not a sumti like {mi} can count as an axis, if not, then you can say {lo mi se carna} or similar. How to specify the point of view when two people are standing on opposite sides of a screen? Unless the screen has a very obvious inherent orientation, the frame of reference can be specified by use of {ma'i}: ko gasnu lo nu lo tivni cu carna fi lo pritu ma'i do "Make it so that the screen turns clockwise from your point of view." Note that lo pritu here refers to what is to the right of point A on the circle, not what's to the right of the listener, even though, if point A were chosen to be the topmost point of the screen, then they would be identical. This will often intuitively be the case, and could even be made a convention (which it already is in math). Finally, we can in good conscience use {pritycarna} and {zulcarna} for "clockwise" and "counter-clockwise" respectively. {carna} is usable for both rotation and turning, which are the same thing. The number of rotations can be specified otherwise, but it doesn't change the relation at hand, which is why we need no new word and can use {carna} for both. mu'o mi'e la selpa'i -- pilno zo le xu .i lo dei bangu cu se cmene zo lojbo .e nai zo lejbo-- You received this message because you are subscribed to the Google Groups "lojban" group. To post to this group, send email to lojban@googlegroups.com. To unsubscribe from this group, send email to lojban+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/lojban?hl=en. |
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