- From: Uschold, Michael F <michael.f.uschold@boeing.com>
- Date: Sat, 5 Mar 2005 09:37:36 -0800
- To: <rector@cs.man.ac.uk>
- Cc: <public-swbp-wg@w3.org>
GENERAL comments
Are you going to redo [some of] the figures using a nicer tool? Some of the text is literally undreadable on my 1600x1200 laptop screen. Contentwise, they are fine. Perhaps Natasha and her MAC-only diagramming tool has set too high a standard - I'm now spoiled :-) .
Below are a bunch of highly specific recommended changes, most are very minor to do with fine tuning. In a few places, I have added a bit more detail. You may disagree with some, due to different writing styles. Take what you like, and leave the rest.
It would have been easier and faster to edit the file directly, but I did not want to edit a non-latest version, in case you are also working on it still. Also, it makes it easy for you see exactly what my suggestions are, and ignore the ones you don't agree with.
NB: I did not check any of the referenced full code examples. Has someone else done that?
Do we want to have this and Natasha's note use the same naming conventions? You use underscore to separate names. In one sense, it is a good idea to use different conventions, showing that this is real life. It could also be confusing for folk reading more than one of our notes. This is a general question for the OEP TF. I lean towards a consistent naming convention, it would even make sense to say exactly what it is. Also, we should point out that we are nto recommending this as the right one, just one among variuos that work just fine.
SPECIFIC comments
Abstract:
Replace "officers and restricted" with "officers and be restricted"
---
Replace "specifies the constraints on the values that the property can take on" with
"specifies what values the property can take on"
---
Replace "methods to represent" with "methods for representing"
OR: replace "methods" with "ways". IMHO: 'way' is preferred, since you use that phrase later: "There are at least three different ways to represent such specified collections of values"
---
GENERAL ISSUE
Replace "health person." with "healthy person."
---
You say:
"It is a common requirement in developing ontologies to be able to represent notions such as a "small man", a "high ranking officer" or a "health person." There are many such "features"..."
"health person" should be "healthy person". More substantively,
This wording suggests that 'small man' is a feature. Is this what you mean? Later you say: "it is necessary to specify the constraints on the values for the "feature" - e.g. that size may be "small", " This suggests the feature is 'size'. Its the difference between the property itself (size) and a property=value assertion (size=small). I don't know what you mean. I'm not sure whetehr you want to gloss over this distinction here (with carful wording), or whether it is worth making. As it stands, it is a bit confusing.
---
Replace:
* As individuals whose enumeration makes up the parent class representing the feature; (See pattern 1).
with:
* As an enumerated set [or list?] of individuals (e.g. small, medium, large) which makes up the parent class representing the feature; (See pattern 1).
Also, add an example to the next bullet like I did for this one.
ALSO: in the phrase "representing the feature"I can't figure out which meaning of feature you are using (size? size=large?). It seems neither. Rather it seems to be referring to the value set of the the property size. Frankly, I don't know what the phrase: "the parent class representing the feature"means. Parent of what? Do you mean "the set of all possible values that the feature(e.g. size) can have"? This is the feature space, which you define later. What does parent have to do with this?
---
Because of this terminology confusion, I think you need to either:
1. move the vocabulary section much earlier in the document.
2. include a forward reference to the vocabulary section very early in the document.
I prefer 1.
---
USE CASE EXAMPLES:
Replace "e.g. it should be inconsistent (unsatisfiable) to be both slender and obese or in good health and poor health" with
"e.g. an inference engine will flag an error if an individual is declared to be both slender and obese or in good health and in poor health"
I replaced the theorem proving lingo with everyday language to convey the point.
---
Replace: "The others follow analogously." with "The solutions for the other examples are exactly analogous."
---
NOTE CONVENTIONS
Much of this section could also go in an appendix. I don't have a preference, works ok either way. Your call. Ideally this will be pulled out and used by more than one note.
I suggest adding a formal TODO on this point. See also my note to the list on this.
---
I would put the vocabulary first, in the conventions section, it is more important.
In fact, it might be better to put the vocabulary in the very beginning, because you use the terms right away.
Also, put partition last, as it is less important (as a bonus, it would also be in alpha order...)
---
Diagramming:
I still don't know what an open or closed arrow means. It is not obvious to me by looking at the different arrows. Perhaps you mean the shape of the arrowhead? The terms open and closed dont convey that to me. Is this a standard terminology for arrows that I am not familiar with?
---
'arrowsor' and 'arrowsindicate'need spaces to separate words.
---
In: "* Downwards facing braces are used to indicate pairwise disjointness between subclasses or owl:allDifferent for individuals. (All sibling classes are disjoint and all individuals of each type are different in these examples.)"
What is the owl symbol if the pairwise disjointness is between classes? Does it ever appear in a diagram? You might address this something like as follows:
Downwards facing braces are used to indicate pairwise disjointness between subclasses or between individuals. These are represented in OWL as owl:?? and allDifferent respectively. (All sibling classes are disjoint and all individuals of each type are different in these examples.)"
This might be an incorrect wording for what you are trying to say.
---
"SWBP" --> "SWBPD" (tut tut)
---
Pattern 1:
To focus on the postive first, replace:
"The second is more complex but is more flexible. Some classifiers also work more reliably with Pattern 2 than Pattern 1."
with
"The second pattern is more flexible, and some classifiers work more reliably with it than with Pattern 1. However, Pattern 2 is more complex."
---
PATTERN 1:
"In this approach, the class Health_Value is".
Why a definite article? This is first mention of this class. Below I suggest a rewording for this pattern which says what to do in more detail. I feel that the readers of this note will find it easier to create their own examples if we give more details on exactly what needs to be done, rather than mainlu just describing what is the case, once you have the pattern. Both are needed.
You may think this too wordy... I made similar changes to approach 4 in the classes as values note. I notice that you have very nice wording in the comments to this effect when presenting the code, that is excellent.
The sentence: "Values are sets of individuals." is slightly ambiguous. 'values' here refers to the feature space, all possible values. But each individual is also a value. I suggest using the term feature space here.
Overall, I suggest the following rewording.
Replace:
"In this approach, the class Health_Value is considered as the enumeration of the individuals good_health, medium_health, and poor_health. Values are sets of individuals. To say that "John is is in good health", is to say that "John has the value good_health for health_status" This assumes that a value is just a unique symbol, and a value set is just a a set of such symbols."
with
"In this approach the feature space is represented as an enumerated set of individual values. The feature of interest is represented as an OWL property (e.g. health_status). We wish to restrict the range of this property to be one of three values corresponding to good, medium and poor health. To achieve this, we create a class that represents the set of all possible values for the given feature, and we enumerate each value. This class (e.g. Health_Value)is defined to consist of exactly three enumerated individuals: good_health, medium_health, and poor_health. The name includes the string "_value" to indicate that this class was specifically created for representing values. Each enumerated individual is an instance of the value class.
To say that "John is is in good health", is to say that "John has the value good_health for health_status". For this pattern, a value is just a unique symbol, and a value class is just a set of such symbols."
---
Are the values 'sets' or 'lists' of individuals? Sometimes order DOES matter, so from a common sense perspective, they are not sets (although, if the order is not formalized, then from a model-theoretic viewpoint, I guess they are sets). Anyway, be consistent.
---
replace:
{{The value set and make it equal to the enumeration of the three individual values}}
with
{{Create the value class and make it equal to the enumeration of the three individual values}}
---
The comment: {{Define each of the individual values as an individual of type Health_value}}
should be boldface, like the others. Check for other examples of font inconsistency.
---
Replace: "Many people find this the more intuitive approach." with
"Many people find this approach very intuitive." because you have not introduced the other pattern yet.
---
Replace
"There is no possibility of further subpartitioning of values." with
"There is no possibility of further subpartitioning of values (e.g. good_health into very good and pristine health)."
Replace:
"It is not possible, as it is for classes, to say that one individual is equivalent to the the union (disjunction) of two other individuals."
with
"It is not possible to say that one individual is equivalent to the the union (disjunction) of two other individuals. An analogous statement can be made with classes."
This may just be style preference; you may not like it. It is longer, but [possibly] slightly more accurate. The problem is, strictly speaking, you cannot, for classes, "say that one individual is equal to the union of two other individuals" You CAN say something very analogous.
---
Replace
"Because individuals cannot overlap, if Health_Value is defined as equivalent to enumeration of one list "
with
"Because individuals cannot overlap, if Health_Value is defined as being equivalent to the enumeration of one list "
---
Replace
"To do so would cause the reasoner to indicate a contradiction. (i.e that Health_Value was "unsatisfiable".)"
with
"To do so would cause the reasoner to find a contradiction and flag an error."
Unless you really want this theorem-prover speak (is it germane to the note?). Whatever you decide, use the same convention throughout, this occurs in more than one place.
---
The last disadvantage starts off sounding like an advantage.
Replace:
"The representation is in OWL-DL, and DL reasoners should eventually be expected to make correct inferences with individuals used in this way. However, neither FaCT nor Racer (the two most widespread open source reasoners in use today) perform all the expected inferences reliably. "
with
"Although the representation is in OWL-DL, currently, neither FaCT nor Racer (the two most widespread open source reasoners in use today) reliably perform all the expected inferences. In the future, reasoners will likely be able to make correct inferences with individuals used in this way. "
Or shorten last sentence even more:
"This limitation will likely go away with improved reasoners.
---
PATTERN 2:
In the title of this pattern, and in the first sentence, you say 'feature' when I think you mean 'feature space'.
---
I don't think the word 'continuous' is accurate because it might not be continuous, it could still be discrete. Or if strictly speaking it is accuarate, it might be misleading.
---
You say: "the Good_health_values partition". The vocabulary definition does not define partition as a noun, just as a verb. You need to amend the definition if you want to use 'partition' as one of the mutually disjoint collectively covering subclasses.
---
The sentence: "Theoretically, there is an individual health value, Johns_health, but all we know about it is that it lies someplace in the Good_health_value partition. " will likely confuse people. I had to puzzle for a while about it, and after reading the code, realized that these two variants are just like the two variants of approach 4 in the classes as values note [exactly analogous, I think]. I think it may be clearer to present pattern 2 here as I [re-]presented approach 4 in the other note. That is: Just describe the first variant as if it is THE approach. And then say, by the way, there is a minor variant... This would entail
1) removing the sentence: "There are two variants presented: one in which the individual Johns_health is explicitly represented, the other in which it is implied by an existential restriction." or moving it to later, as a summary remark.
2) removing the header: "Representation variant 1: Using a fact about the individual"
3) adding an introductory remark for the 2nd variant.
4) do something about the Venn diagram. It will need to be moved to after the variant, or simplified to leave out the restriction. The restriction is pretty confusing, in that diagram, so I suggest the latter option. Have every arrow represent an simple instance of the binary relation: has_health_status. Maybe add more named individuals?
btw: The 'J' in "Johns_health" is a different font.
---
The Healthy_Person class seems an optional, rather than essential part of this pattern. Perhaps this could be indicated?
---
Here is a suggested rewrite taking into account the above comments; it is modeled after the rewrite for pattern 1. I also emphasize what is similar and different about this pattern and the first.
Replace:
"In this approach we consider the feature as a class representing a continuous space that is partitioned by the values in the collection of values. To say that "John is in good health" is to say that his health is inside the Good_health_values partition of the Health_value feature. Theoretically, there is an individual health value, Johns_health, but all we know about it is that it lies someplace in the Good_health_value partition. The cass Healthy_Person is the class of all those persons who have a health in the Good_health_value partition."
with
===
"In this approach, the feature space is represented as a value class partitioned by a group of subclasses (e.g. Good_health_value Poor_health_value). As for pattern 1, we represent the feature of interest (has_health_status) as an OWL property, and we create a value class (Health_Value) that is used to restrict the range of the property. The key difference is in how we represent the values and the value class. The allowed values (good, medium and poor health) are represented as subclasses, not individuals. The value class is defined as the union of these subclasses.
Using this pattern, to say that "John is in good health" is to say that the value representing his health_status (e.g. Johns_health) is contained in the Good_health_value partition of the Health_value feature space. Formally, Johns_health is an instance of the value class: Good_health_value.
We can also create a class called Healthy_Person, defined to be the class of all persons whose health_status has a value in the Good_health_value partition. In this case, the classifier can infer that John is in that class."
===
NB: Although I spent a lot of time on this, I am still not entirely happy with this wording, it loses some of the simplicity of your text, in the attempt to be more precise. Perhaps there is a best of both world middle ground that you can find?
BTW: you are using plural for the names of some of the classes. I fixed them, they are correct in the figures (singular).
---
Not all of the comments in the Code for this example are the same font.
---
You use the term 'parent value class'. It is a parent class, from a graph-theoretic point of view, but from the user's point of view, it is the class representing the main/whole feature space. The 'child' value classes represent portions of the whole feature space.
I suggest not using the word parent. [minor style point]
---
Replace: "you make the individual a type of the restriction."
with "you make the individual an instance of the restriction."
---
Fig 3: you refer to "lists of values" change to sets?
---
The wording: {{The disjoint axioms make the subclasses partitioning}} seems a bit akward. Maybe you were doing a dance with terminology...
Perhaps try:
to {{The disjoint axioms make the subclasses partition the value class: Health_Value}}
Also, move this comment to immediately after the followign comment,because it applies to all three subclass definitions:
"{{Define each of the subclasses that make up the partitioon and make them pairwise disjoint}}"
Better yet, skip that comment, it is probably unnecessary, given the one above.
And fix: 'partitioon'
---
There is a missing full stop after the definition of "medium_health_value".
---
In the comment for defining healthy person, note that it is not mandatory for the pattern (or if it IS, can you tell me why?).
---
Suggested indenting tweak to make things more clear what the two classes are that are being intersected. It took me a while to puzzle it out. This might be too much work in general, if automatically generated...
:Healthy_person
a owl:Class ;
owl:equivalentClass
[ a owl:Class ;
owl:intersectionOf (:Person
[ a owl:Restriction ;
owl:onProperty :has_health_status ;
owl:someValuesFrom :Good_health_value
])
] .
---
Figure 4: minor tweak. Highlight exactly what is different with this figure, compared to figure 2. Make the new part blue, or in bold? Maybe add text somewhere or caption the figure to say exactly what changed with this variant:
1. instance now implied, not explicit (noted by dotted lines)
2. new arrow from john to good_health_value
[maybe overkill, it is pretty clear just by looking at it...]
---
reasoner and reasonable in same sentence (stylistic quibble). maybe use inference engine or classifier isntead of reasoner?
---
Give a simple example of alternate partitionings for the same feature space. A real life example that turned up in Boeing was dividing up the fuselage into [front, middle, rear] and [front, back]. Each was a partition. The problem arose because we needed to do a semantic mapping, which of course is inherently ambiguous.
---
The following seems contradictory:
"If variant 2 is to be used as part of a database schema or similar, then a convention for creating anonymous instances in the database is required. (Logicians call such anonymous instances "skolem constants".) In practice, this can usually be ignored."
If you can ignore it, then a convention is not required.
This point is fairly lost on me, I can't follow what you are getting at.
---
WELL, I don't know what happened, someone must have slipped a much finer toothed comb in my pocket - I didn't think there would this much more additional feedback...
Despite all the verbiage, I really like the note, all this is just fine tuning.
Mike
Received on Saturday, 5 March 2005 17:43:19 UTC