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From: gadi@SHUM.HUJI.AC.IL (Gad Aharoni)
Newsgroups: comp.lang.misc
Subject: Re: C's sins of commission
Message-ID: <393@shum.huji.ac.il>
Date: 15 Oct 90 11:10:54 GMT
References: <387@shum.huji.ac.il> <65664@lanl.gov>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: shum!gadi@lilac.berkeley.edu (Gad Aharoni)
Organization: The Hebrew University of Jerusalem
Lines: 25

In article <65664@lanl.gov> jlg@lanl.gov (Jim Giles) writes:

>... Graphs are easy
>to implement as recursive data structures without any user-visible
>variable whose value is an address - that is to say: without explicit
>pointers.

Ok. Show me how you would implement a graph data structure without using
pointers, and when I say pointers I also mean array indices.

The only other way I can think of is to use the standard logic, or
relational database technique of listing the dependencies. I am not
too fond of this method of representing a graph because when a path
in the graph is followed, the next node is not "at hand". When a list
is followed the next element is always there, when following the right
son of a tree, the subtree is there, at hand, immediatly accessible.
In this method of representing a graph the next node has to be searched
for in the table before the node is accessed. This is in fact simulating
store, only without the advantage of immediate access.

Gadi
--
Gad Aharoni                                              TEL: +972-2-584932
BITNET: gadi@humus.bitnet           CSNET & INTERNET: gadi@humus.huji.ac.il
Snail: Dept. of CS, Hebrew University of Jerusalem, Jerusalem 91904, Israel