Talk:Polish notation

message: This stub is confusing. The notation for existential quantifier ($x)Gx does not seem to match the notation used in the artical.
Also, postfix notation redirects to Reverse Polish Notation
but   Polish notation redirects to prefix notation.
I am tempted to fix this but the stub does not seem to say much on the general concept of prefix notation, and I don't think my maths is up to it.
-- Chris Q 09:39, 20 Nov 2003 (UTC)
thread_title: Query

message: The note about this being used in Tcl is rather misleading. math in Tcl is in infix notation, but the language syntax is polish notation. Being this is a math article and when I first read the line, I became rather confused at what it meant. Could someone re-word this to read more clearly? I'm unsure how to word it myself. — Striker 22:48, 5 December 2005 (UTC)
thread_title:  Tcl 

message: :The "conventional" notation did not become so until the 1970s and 80s.
Does this mean to say that "The (common OR currently used) notation did not become conventional until the 1970s and 80s." or somesuch? - Centrx 22:59, 21 May 2006 (UTC)
thread_title:  Question about sentence 

message: This page is written in a strange tone. I don't think it's good form to use the word "we" in an article (just as an example). Mo-Al 06:19, 25 June 2006 (UTC)
thread_title:  Tone 

message: The article reads : 
"Although obvious, it is important to note that the number of operands in an expression must equal the number of operators plus one, otherwise the statement makes no sense (assuming only binary operators are used in the expression). This can be easy to overlook when dealing with longer, more complicated expressions with several operators, so care must be taken to double check that an expression makes sense when using Polish notation."
I'm not sure I understand it, can someone please add an explanation or confirm if it's a mistake?
:It means that the number of things getting operated on is the number of operators + 1. For example, in "+ 1 2", "+" is the operator, and "1" and "2" are the operands. Mo-Al 02:40, 12 August 2006 (UTC)
thread_title:  Is this a mistake? 

message: I'm reading this article, and towards the end it gives examples of association and distribution. For each it offers a more polish way of writing the statement of equivalence, using "=" as a binary operator.
I'm not sure that this use is appropriate, because it renders the equivalence confusing (and I have never seen this usage before... which does not mean it is incorrect, of course). Slightly Drunk 19:58, 4 January 2007 (UTC)
thread_title:  In a more technically polish way 

message: *As a formal student of Philosophy and Logic in the United States, I have always known this subject by its former name.
Furthermore, Google shows us the former is far more common.
:Accordingly, I'm recommending that the Title of this Article be changed to the former. Yours truly, --Ludvikus 00:08, 13 October 2007 (UTC)
replies: text: *76,900 Google hits for "Prefix notation": . --Ludvikus 00:14, 13 October 2007 (UTC)

text: *155,000 Google hits for "Polish notation":  --Ludvikus 00:17, 13 October 2007 (UTC)
replies: text: Should we also change all occurences of "prefix notation" (but not necessarily "prefix expression") to "Polish notation" in the article? I think we should either do that, or change the "or less frequently known as 'Prefix notation'" in the first sentence to "also known as 'Prefix notation'" (although the former is true, the article doesn't call it that "less frequently" than the alternative). --Spug (talk) 01:04, 12 December 2007 (UTC)

text:  I think the article should be called Prefix notation since it is country neutral. Accordingly, Reverse Polish Notation should be Postfix notation. 68.239.247.134 (talk) 05:24, 27 December 2009 (UTC)
thread_title:  [[Polish notation]] vs. [[Prefix notation]] 

message: We should probably rewrite these sections; they overlap, and the former describes RPN as used in many stack-based programming languages, while the former says that PN is especially popular with those languages. --Spug (talk) 01:01, 12 December 2007 (UTC)
thread_title:  Sections "Computer programming" and "Order of operations" 

message: The statement "In the previous example, the parentheses in the infix version were required, since moving them 
(5 − 6) + 7
or simply removing them
5 − 6 + 7
would change the meaning and result of the overall expression."
This is not true. Addition is associative - the parentheses don't matter! This would be true if addition and multiplication were mixed: 
5 - (6 * 7) <> (5 - 6) * 7 
Jesse1919 (talk) 03:37, 24 February 2008 (UTC)
thread_title:  example is incorrect? 

message: Is Polish notation also referred to as "Polish logic," or does/can that term have a different meaning? The article Polish Logic, about an anthology, has a hatnote pointing to this article. -- ℜob C. alias ᴀʟᴀʀoʙ 18:39, 7 September 2008 (UTC)
thread_title:  Polish logic == Polish notation? 

message: is there an algorithm to convert infix to prefix?—Preceding unsigned comment added by 72.68.199.83 (talk) 05:04, 3 March 2009 (UTC)
replies: text: Certainly. For example, construct the parse tree of the infix formula, and traverse it in preorder.—Emil J. 15:45, 18 October 2010 (UTC)

text: See Shunting-yard algorithm. —Bkell (talk) 16:19, 18 October 2010 (UTC)
thread_title:  Conversion of Infix to Prefix notation 

message: The mention of Lisp doesn't seem relevant, because Lisp doesn't use parentheses-free Polish notation even when possible. The Lisp version of infix expression 5 • 2 ÷ 3 + 8 ÷ 7 is (+ (* 5 (/ 2 3)) (/ 8 7)), not + * / 2 3 5 / 8 7. This is in contrast to stack-based, prefix languages like Forth, which really use reverse Polish notation. 152.1.137.158 (talk) 15:06, 15 April 2016 (UTC)
thread_title:  Lisp and other 'prefix' languages 

message: The current evaluation algorithm that process the expression from left to right is wrong. Counterexample: 
 infix notation: 2*(5*2 + 1)
 prefix notation: * 2 + * 5 2 1
 expected evaluation: 22
 obtained evaluation: 12
 actually evaluated expression: (2 + 5*2)*1
The "push-down automaton with shift reduce rules" is the correct algorithm for this situation. This algorithm needs a finite state control that keeps track of what is on top of stack, and typically, the current state also need to be pushed on the stack. I guess it may be implemented with a operand counter. It can be a rather complex algorithm, therefore removal may be a better solution.
Proto8170 (talk) 07:57, 29 September 2018 (UTC)
replies: text: I'm not really into single stepping this "algorithm", and I also do not want to involve myself in checking your results. I'm also no expert in " shift reduce rules", but introduced the DPDA in the text. Your remarks about the finite control (keeping track, pushing states, operand counter) rather confuse me, and I object to this being a "complex algorithm". I would not object to removing this elaborate example, but in case it is right, some readers might lose a guide. Purgy (talk) 12:42, 1 October 2018 (UTC)

text: You're right, the algorithm is wrong. I did the calculation step-by-step on your example and confirmed your result.  Anyway, as far as I can see, the whole section #Explanation as well as #Prefix evaluation algorithm together with its subsection #Example possibly fulfill WP:NOR criteria for what should not appear in Wikipedia. It's a pity, the more I myself expanded some part of them – but they actually remain absolutely unsourced. --CiaPan (talk) 20:40, 1 October 2018 (UTC)
replies: text: With three editors talking about deletion of the example, I simply was bold. However, I object to removing #Explanation as well as the whole former #Prefix evaluation algorithm. It never would come to my mind to consider this as "original research", these are trivial consequences ("simple calculations") of the way the notation is set up, where there are certainly thousands of reliable sources in the wild. I'd assume there must be even a Knuth among them. Purgy (talk) 07:04, 2 October 2018 (UTC)
thread_title:  Wrong evaluation algorithm 

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message: No love for APL? 2A01:CB0C:CD:D800:D890:8BF2:2502:B9F0 (talk) 07:54, 16 September 2022 (UTC)
thread_title:  Implementations 

message: An editor has identified a potential problem with the redirect :Noitaton Hsilop and has thus listed it for discussion. This discussion will occur at Wikipedia:Redirects for discussion/Log/2022 September 16#Noitaton Hsilop until a consensus is reached, and readers of this page are welcome to contribute to the discussion.  Steel1943 (talk) 22:04, 16 September 2022 (UTC)
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