Dennis Lee Bieber <wlfraed@ix.netcom.com> writes: > > of change in state. The "event" in TMG apparently remains tied to static > > data. Is any kind of event allowed besides the obvious ones of birth, > > marriage and death? > > > What would you like? Don't pay too attention to my remark, which percipitated from my primary concern for historiography and the "event" in that context. In that context, it is in principle possible to escape a static view, but I'm not sure about genealogy, which to some extent is primarily concerned with data. >> No, I wasn't thinking of a heap. A heap is an array or tree structure >> that orders people according to lineage. It seems very old fashioned > > I'd call that a hierarchical file structure... or simply a tree. At > least when I took comp.sci., a heap file was just that -- an unsorted > stack of dis-similar records; one had to read the record in order to > even figure out what the data represented. Interesting. We are appparently speaking of the same thing. When I took my Data Structure course, we encounted the "heap" as (quote from my textbook). A heap is a binary tree with these characteristics: * It's complete. This means it is completely filled in... * It's (usually) implemented as an array. ... * Each node in a heap satisfies a heap condition, which states that the node's key is larger than (or equal to) the keys of its children. In my notes on databases, I have: A heap is a specialized tree-based data structure that satisfies the heap property: if B is a child node of A, then key(A) ≥ key(B). As you point out, there is no suggestion that record B has any similarity to record A here. The only condition is that the key value for record A must be at least as great as the value of the key of record B. This struck me as somewhat descriptive of a family hierarchy in that there are generations, especially today when any biological relation of families or generations is unclear, and even surnames can be only loosely related to biological descent. For example, only one of my 28 grandchildren and 5 great-grandchildren are actually my biological descendents because I live in a culture in which "family" has little to do with biology and more to do with a political decision (much like "tribe" used to be). And yet there seem to be clear generational demarcations (as long as we can forget the etymological meaning of "generation"). So I have to take back my comment about heap tree being suited to lineage. It may better suit social relations today that are not so lineage-based. >> Incidentally, what kind of data structure is used in TMG? Do all >> genealogical applications use the same data structure? >> > TMG is built upon Visual FoxPro tables. Very many of them -- > approximately 29 separate tables. Interesting; I remember FoxPro from back in the 90s. Is Microsoft dropping support for it because VFP runs under wine? How will that affect TMG? It sounds like it is a relational database that has a table interface. Is that so? I assume it is more than spreadsheets. > None of the genealogy programs I'm familiar with can "modify" > data /in/ a raw GEDCOM. They all perform batch loads into a database > schema -- where data is not a sequential text format -- manipulate the > data in that format, store the data in that database, etc. OK, as I suspected. LifeLines does this as well, although it looks as though one were modifying raw GEDCOM. -- Haines Brown, KB1GRM