The attached worksheet shows a simple operator to calculaute the cartesian product of a set. The code is executed in both 1D and 2D notation in the worksheet.  The code is also placed in a code edit region and in the startup code area if the worksheet.  When entered into a worksheet is either notation, it produces an error message,  Without the local designation, it executes with a warning message. When entered into a code edit region it executes without error or warning.

I assume that this behavior reflects a limitation of the 2d notation or is there a workaround to the problem?

error4.mw

I installed Maple 2023.1 update and immediately noticed a problem with the worksheet editor.

Specifically, the editor seems to be replacing "<" with "!" in the maple code. I first noticed the problem with code copied from the maple code editor into a worksheet, but then noticed the same problem with code on another worksheet which was loaded from file. Thus, it seems the problem is actually in the worksheet editor and not the copy paste function.  Note that the problem occurred immediately on reloading files after I restarted maple from the update. Normally, when this occurs, it starts after Maple has been loaded for an hour or more. Fortunately, when I restarted Maple and reloaded files, the problem seems to have cleared itself.

I have attached images showing the maple screen with the error, and also the specific code copied from the code editor to a worksheet for comparison.  I have also attached the worksheets in which I saw the problem. For now my goto workaround is to save and restart because the problem does not seem to corrupt the actual files even when I save them.

Attachments: chain.mw  chain2.mw

The example worksheet uses table to determine the covering relations in a POSET. This is old (Maple 11 and earlier code) that I have been trying to update into a package to explore calculations in an algebraic structure.  The example procedure seems to work well, but because of problems with similar procedures elsewhere, I have some concerns about the validity of using tables in this fashion. Specifically, this procedure initializes a table, then proceeds to modify the table entries, and then reformats the sequences into sets.  I have not been able to find documentation for modifying entries in tables after they have been defined. The documentation for tables only covers adding entries, removing entries, but not modifying entries.

Is modifying tables as my  procedure does an undocumented feature?

In addition, the documentation does not explain how to clear a table. It only describes how to clear a table entry. Older code sometimes purported to clear a table by assigning its name (with uneval quotes) to itself, but this does not seem to work.

exampletableoperations.mw

If there is a list of operations that do not work properly in 2D notation, please add the expression sequence operator `$` which does not work with strings as demonstrated in the attached worksheet . sequenceoperastionfailure.mw

It seems to work properly with numeric sequences. I only noticed this in maple 2023, but it likely applies to earlier versions as well

The attached worksheet contains expressions that cause a warning message to appear in my worksheet.  In another post it was suggested that the variable i should be explicitly declared local in the definition of the arrow expression. However, as shown in the same worksheet, this gives rise to an error message. Subsequently, I found a statement in help that suggested this approach would not work in 2-d math notation.  Are there any other ways of eliminating these warnings in 2-d math notation?

warningmessage.mw