On Mar 1, 3:00 am, Kiuhnm <kiuhnm03.4t.yahoo.it> wrote: > They did not make up the terminology, if that is what you are saying. > The concepts of left and right associativity are well-known and accepted > in TCS (Theoretical CS).
> Aho, Sethi and Ullman explain it this way in "Compilers: Principles, > Techniques and Tools": > "We say that the operator + associates to the left because an operand > with plus signs on both sides of it is taken by the operator to its > left. [...]" > And they also show parse trees similar to the ones I wrote above. how do they explain when 2 operators are adjacent e.g. 「3 △ 6 ▲ 5 」? do you happen to know some site that shows the relevant page i can have a look? thanks. Xah On Mar 1, 3:00 am, Kiuhnm <kiuhnm03.4t.yahoo.it> wrote: > On 3/1/2012 1:02, Xah Lee wrote: > > > i missed a point in my original post. That is, when the same operator > > are adjacent. e.g. 「3 ▲ 6 ▲ 5」. > > > This is pointed out by Kiuhnm 〔kiuhnm03.4t.yahoo.it〕 and Tim Bradshaw. > > Thanks. > > > though, i disagree the way they expressed it, or any sense this is > > different from math. > > They did not make up the terminology, if that is what you are saying. > The concepts of left and right associativity are well-known and accepted > in TCS (Theoretical CS). > > If you change the terminology, no one will understand you unless you > provide your definitions every time (and then they may not accept them). > > Another way of saying that an operator is left-associative is that its > parse tree is a left-tree, i.e. a complete tree where each right child > is a leaf. > For instance, (use a monospaced font) > 1 + 2 + 3 + 4 > gives you this left-tree: > + > + 4 > + 3 > 1 2 > while 1**2**3**4 > gives you this right-tree: > ** > 1 ** > 2 ** > 3 4 > > Aho, Sethi and Ullman explain it this way in "Compilers: Principles, > Techniques and Tools": > "We say that the operator + associates to the left because an operand > with plus signs on both sides of it is taken by the operator to its > left. [...]" > And they also show parse trees similar to the ones I wrote above. > > Kiuhnm -- http://mail.python.org/mailman/listinfo/python-list
