Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #1 2014-01-26 05:54:34

evinda
Member
Registered: 2013-04-13
Posts: 105

### How can I know the number of all the possible parse trees?

Hello!!!
Let

the following grammar with
and with start symbol
:

I have to make all the possible parse trees for the word

But how can I know how many possible parse trees there are?Is there a formula with which I can find the number of all the possible parse trees?

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## #2 2014-01-26 08:00:06

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: How can I know the number of all the possible parse trees?

I think there are 6 of them here, since the difference between the trees will be in which order do you go through the operations (that is, those elements that correspond to P). You can go -+*,-*+,+-*,+*-,*-+ or *+-.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #3 2014-01-26 10:58:38

evinda
Member
Registered: 2013-04-13
Posts: 105

### Re: How can I know the number of all the possible parse trees?

anonimnystefy wrote:

I think there are 6 of them here, since the difference between the trees will be in which order do you go through the operations (that is, those elements that correspond to P). You can go -+*,-*+,+-*,+*-,*-+ or *+-.

Ok..thank you very much!!!

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## #4 2014-01-26 11:07:46

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,588

### Re: How can I know the number of all the possible parse trees?

I don't know this stuff, but is the "/" being missed here?

igloo myrtilles fourmis

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