7. Dimensionality: VIhA

   vi'i    VIhA    on a line
    vi'a    VIhA    in an area
    vi'u    VIhA    through a volume
    vi'e    VIhA    throughout a space/time interval

What about the child walking on the ice in Examples 5.1 through 5.3? Given the nature of ice, probably the area interpretation is most sensible. I can make this assumption explicit with the appropriate member of selma'o VIhA:

7.1)  le verba ve'a vi'a
        cadzu le bisli
    The child [medium space interval] [2-dimensional]
        walks-on the ice.
    In a medium-sized area, the child walks on the ice.

The reader may wish to raise a philosophical point here. (Readers who don't wish to, should skip this paragraph.) The ice may be two-dimensional, or more accurately its surface may be, but since the child is three-dimensional, her walking must also be. The subjective nature of Lojban tense comes to the rescue here: the action is essentially planar, and the third dimension of height is simply irrelevant to walking. Even walking on a mountain could be called ``vi'a'', because relatively speaking the mountain is associated with an essentially two-dimensional surface. Motion which is not confined to such a surface (e.g., flying, or walking through a three-dimensional network of tunnels, or climbing among mountains rather than on a single mountain) would be properly described with ``vi'u''. So the cognitive, rather than the physical, dimensionality controls the choice of VIhA cmavo.

VIhA has a member ``vi'e'' which indicates a 4-dimensional interval, one that involves both space and time. This allows the spatial tenses to invade, to some degree, the temporal tenses; it is possible to make statements about space-time considered as an Einsteinian whole. (There are presently no cmavo of FAhA assigned to ``pastward'' and ``futureward'' considered as space rather than time directions --- they could be added, though, if Lojbanists find space-time expression useful.) If a temporal tense cmavo is used in the same tense construct with a ``vi'e'' interval, the resulting tense may be self-contradictory.