Re: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?
Op dinsdag 27 juli 2010 21:07 schreef karl williamson: They are U+2107 and U+210E respectively. Chapter 4 of TUS seems to indicate that neither should, since they both are operands, and it says this property applies to mathematical operators. Operands are not operators, e.g. in a+b, a and b are operands, + is an operator. Alex.
RE: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?
Alex notes Operands are not operators, e.g. in a+b, a and b are operands, + is an operator. I'm sure Karl Williamson knows that, but the mathematical alphanumerics also aren't operators and they nevertheless have the math property. We need to change the description of the math property to include all characters that are used primarily for math and the EULER CONSTANT is such a character. Alex.
RE: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?
Murray Sargent murr...@exchange.microsoft.com wrote: Alex notes Operands are not operators, e.g. in a+b, a and b are operands, + is an operator. Not always true, this depends on the domain of definition, see below, and all operators can also be themselves operands of another operator. The generic term for them should be functional objects. (with the same assumption made in computer functional languages that use this formalism). All these functional objects can be considered as constants (or values) or as functions modifying the nature or value of the surrounding functional objects to create a new functional object as the result of their combination. Whever they are constant or not depend on the domain of definition (which is not always exposed in all formulas, and often implied by the context. I'm sure Karl Williamson knows that, but the mathematical alphanumerics also aren't operators and they nevertheless have the math property. We need to change the description of the math property to include all characters that are used primarily for math and the EULER CONSTANT is such a character. The important word of your sentence is primarily, which just means mostly for maths but it should be for scientific formal notations, and not for written orthographies of humane language. Maths can use any character in the UCS it wants (or more exactly any grapheme cluster that can be built with UCS characters, plus a few specific combining characters). And it will continue to create new symbols, and there are certainly many of them that have still not be discovered in some books or scientific paper, that will be encoded later). Given that also the General category is stable (and also th fact that some humane orthography may choose to borrow some symbols currently encoded as Maths symbols within its alphabet, or a convenient abbreviation signs), this general category is the wrong tool for us. So we may need a custom property (but NOT subject to the stability policy) to reference characters that are CURRENTLY considered as NOT being used in humane languages, but mostly for mathematic/scientific notations, even if these lette-like symbols were created from a script for humane languages : they are used only for their symbolic value (and do not obey to the linguistic rules such as collation mappings, case mappings...). The hbar symbol is such a character. Such a property would be useful to exclude, in an implementation of a specific version of Unicode, these characters from normal linguistic processing, in order to protect them from alteration. And it would also be useful if ever, later, some humane language starts getting written using the symbol, and starts applying linguistic features such as collation mappings and case mappings : In that case the symbol should remain stable, and the linguisitic letters should be encoded separately, unless there's evidence that too many texts are already using the maths symbol directly (in which case, this symbol will be removed from the custom scientific-only category defined by the custom (non stable) property. Note that in maths, there's no really any distinction between operators and operands. They are just symbols having a functional behavior and an implied associativity (on left or right, or both, depending on the notation used). It's impossible to predict the associativity and use of any symbol without knowing the context of use, and without knowing the domain of definition of these functional objects. Philippe.
Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?
They are U+2107 and U+210E respectively. Chapter 4 of TUS seems to indicate that neither should, since they both are operands, and it says this property applies to mathematical operators.
Re: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?
Karl Williamson asked: Subject: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does? They are U+2107 and U+210E respectively. Because U+210E PLANCK CONSTANT is, to quote the standard, simply a mathematical italic h. It serves as the filler for the gap in the run of mathematical italic letters at U+1D455. All of the mathematical alphanumeric symbols are given the Other_Math property, and so also the derived Math property. And for consistency, any of the mathematical alphanumeric symbols omitted from the Mathematical Alphanumeric Symbols block, because the corresponding font-styled variant had already been encoded in the Letterlike Symbols block, are also given the Other_Math property. Other letterlike symbols in that block are not given the Other_Math property, even if they may be used in mathematical expressions. (Note that regular Greek letters are also not given the Other_Math property, even though they obviously also occur in mathematical expressions.) The Math property can be thought of as a hint that a particular symbol is specialized for mathematical usage; it isn't a property that any character that ever occurs in a mathematical expression needs to have. Nor is every character with the Math property only used in mathematical contexts. Chapter 4 of TUS seems to indicate that neither should, since they both are operands, and it says this property applies to mathematical operators. Actually, Chapter 4 no longer says anything about the Math property. It is discussed in Section 15.4, Mathematical Symbols. That text still says: The mathematical (math) property is an informative property of characters that are used as operators in mathematical formulas. Technically it doesn't say that it is a property *only* of such operators -- and obviously it isn't when you examine the actual list, since nobody considers the long list of mathematical alphanumeric symbols to be operators. So it might be nice if someone would propose an update to that text to better describe the actual set and so as not to give the misleading impression that it applies *only* to operators. Incidentally, much more detailed information about the classification of Unicode characters for math is available in the data file associated with UTR #25: http://www.unicode.org/Public/math/revision-11/MathClassEx-11.txt The contents of that file is not limited just to characters with the value Math=True. --Ken
Re: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does?
On 7/27/2010 3:02 PM, Kenneth Whistler wrote: Karl Williamson asked: Subject: Why does EULER CONSTANT not have math property and PLANCK CONSTANT does? They are U+2107 and U+210E respectively. Because U+210E PLANCK CONSTANT is, to quote the standard, simply a mathematical italic h. It serves as the filler for the gap in the run of mathematical italic letters at U+1D455. Correct - they form a set and need to be treated consistently. Other letterlike symbols in that block are not given the Other_Math property, even if they may be used in mathematical expressions. (Note that regular Greek letters are also not given the Other_Math property, even though they obviously also occur in mathematical expressions.) For Euler Constant and Weierstrass elliptic function, this doesn't make a lot of sense, as these are explicitly mathematical characters, not characters that are also used in mathematical expressions. I have put in a formal proposal to add these two (2107 and 2118) to the list of characters with the math property. The Math property can be thought of as a hint that a particular symbol is specialized for mathematical usage; it isn't a property that any character that ever occurs in a mathematical expression needs to have. Nor is every character with the Math property only used in mathematical contexts. One way to look at this property is as a way to help detection of mathematical expressions in running text. Characters that are primarily used for mathematical purposes, or prominently used there, should be included. Characters that are heavily used in ordinary text, with non-mathematical uses should be excluded. A./
