Robin Lee Powell wrote:
On Wed, May 30, 2012 at 06:46:28PM -0400, Bob LeChevalier, President and Founder - LLG wrote:Robin Lee Powell wrote:The direction words (pritu, zunle, trixe, etc) are phrased very strangely: zunle = x1 is to the left/left-hand side of x2 which faces/in-frame-of-reference x3. What does "which faces" mean? It seems to imply that x2 must have a natural facing/front, which is bad. Why do we even care about facing in this contexnt?Pretend that you are multilaterally symmetrical, and that you have no front. Identify what is to your left. Now rotate yourself 180 degrees, and what is "to your left" is what used to be "to your right". Thus your orientation/facing/frame of reference, is essential to defining what "to your left" means.Obviously, but why is that a feature of the *x2*, instead of the *x3* which is the frame of reference? In other words, please describe this picture using {pritu}, and fill all places (feel free to fill some places inspecifically): http://ynevar.files.wordpress.com/2010/04/apple-and-orange.jpg
Ah. Your example shows me the problem. There are three and not two objects that are relevant here - an apple, and orange, and an observer, whose orientation and relationship to the apple and orange (or their image) determines what is to the left.
The basic concept for direction words presumed that the observer/observation origin had to be specified. The norm that we had in mind was the situation where x2 is the observer, and his/her orientation is critical to what is left/right.
When comparing two objects, neither of which is the observer, the observer becomes part of x3 (though how to phrase frames of reference places in Lojban was something that I never seriously tackled).
So:The orange is to the left of the apple in frame-of-reference "the photograph as displayed on the website seen by a standard observer" (if you turn the image upsidedown, then x1 and x2 change, likewise, if you are standing on your head (or in space) with the image displayed normally (but you would modify x3 to indicate an inverted observer).
If I were seeing the fruit live in front of me on my keyboard, then the frame of reference would be fully specified as "me as observer, adjacent to my computer table facing the front of my computer while vertically aligned with earth's gravity field" (If I were on the other side of the table, or upside down, x1 and x2 would be reversed)
If I were the apple, then the orange is to the left of me in frame of reference "away from the photographer", which is actually what we considered the most basic direction concept with observer-centric x2. But if I, the apple, were facing towards to photographer, the orange would be to my right.
None of which tells me why the x3 is there; it seems utterly superfluous.
As I hope is clear from my examples, the x3 is vital because left and right have no meaning without a frame of reference.
x3 is less important for the cardinal direction words (snanu, etc) because in most instances the x3 is standard (i.e. earth normal). There are situations (such as magnetic directions from northern Alaska) where you might use a different frame of reference and get a different direction, (as well as off-planet where cardinal directions might be arbitrarily defined).
-- Bob LeChevalier lojbab@lojban.org www.lojban.org President and Founder, The Logical Language Group, Inc. -- 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.