What is the difference between set and class?

[DBC User]

I am interested in learning the difference between set (theory) and a
class.
For example, if I have a class say Person and it has a specialised
class student and say sue is an instance of student.

Then as per set theory, Student is a subset of Person and Sue is
element of student/Person. I can see how instance and specilisation
can be represented in set theory. But I can not find a difference.
Could some one help me?

Thanks.

[Stefan Ram]

Post by DBC User
I am interested in learning the difference
between set (theory) and a class.

The meaning of these notions if given by their theory.

For example, the von Neumann-Bernays-Gödel set theory

http://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Bernays%E2%80%93G%C3%B6del_set_theory

includes classes as well as sets; classes are entities that
have members but that cannot be members of anything.

Possibly, this is not the notion of class you wanted to
refer to.

However, for an elaborate discussion you need to give the
theory or specification each of your notion stems from as a
(reference to a )specific text.

Usually theories are disjunct, so the notion of a class
in the above set theory can not be the same as the notion
of class in the Java language specification.

For example, a Java class might be »public« or »private«,
while a set or a class in the above set theory does not
have such a property.

[DBC User]

Post by Stefan Ram

Post by DBC User
I am interested in learning the difference
betweenset(theory) and aclass.

The meaning of these notions if given by their theory.
For example, the von Neumann-Bernays-Gödelsettheory
http://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Bernays%E2%80%93G%C3...
includes classes as well as sets; classes are entities that
have members but that cannot be members of anything.
Possibly, this is not the notion ofclassyou wanted to
refer to.
However, for an elaborate discussion you need to give the
theory or specification each of your notion stems from as a
(reference to a )specific text.
Usually theories are disjunct, so the notion of aclass
in the abovesettheory can not be the same as the notion
ofclassin the Java language specification.
For example, a Javaclassmight be »public« or »private«,
while asetor aclassin the abovesettheory does not
have such a property.

Now that I understood the set and class, could you please explain me
the difference between metaclass and class in set theory??

Thanks.

[Stefan Ram]

Post by DBC User
Now that I understood the set and class, could you please
explain me the difference between metaclass and class in set
theory??

(Usually, it makes sense only to quote some lines of a posting
that you directly refer to - but not the complete posting.)

The meaning of »class« and »metaclass« depends on the specific
set theory - there are several set theories.

Moreover:

Numbers have a difference, e.g., the difference between 4 and
2 is 2 (or -2 depending on the point of view).

Notions, in general, do not have a difference.

For example, what is the difference between the moon and
the statue of liberty? This difference is not defined.

In a specific set theory (this topic would actually belong to
sci.math), even if it has concepts of »class« and »metaclass«,
there usually will not be a well defined /difference/ between
these two concepts.

[Stefan Ram]

Post by DBC User
I am interested in learning the difference
between set (theory) and a class.

The meaning of these notions is given by their theory.

For example, the von Neumann-Bernays-Gödel set theory

http://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Bernays%E2%80%93G%C3%B6del_set_theory

includes classes as well as sets; classes are entities that
have members but that cannot be members of anything.

Possibly, this is not the notion of class you wanted to
refer to.

However, for an elaborate discussion you need to give the
theory or specification each of your notion stems from as a
(reference to a )specific text.

Usually theories are disjunct, so the notion of a class
in the above set theory can not be the same as the notion
of class in the Java language specification.

For example, a Java class might be »public« or »private«,
while a set or a class in the above set theory does not
have such a property.

[panu]

... The meaning of these notions is given by their theory.
For example, the von Neumann-Bernays-Gödel set theory
http://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Bernays%E2%80%93G%C3%B6del_set_theory
includes classes as well as sets; classes are entities that
have members but that cannot be members of anything.

In the context of OO-languages, a CLASS is something
that acts as a template, a cookie-cutter, for creating
objects associated with that class called its 'instances'.

A Set is a more general term which more or less refers
to a *group of objects with some common properties*.

The programming concept of Set is different though.
In a programming language the class (!) Set is defined
by *code* written in that language. Thus it is defined
truly formally.

I've often wondered, what would happen if we tried to
program Russell's paradox in an OO-language. Probably
an infinite loop, right? And if so, wouldn't that
show that 'paradoxes' are nothing very mystical
after all, just programs that never terminate.

In other words, if Russell had had access to a modern
programming language, he might have had the insight
that all definitions are programs, and it makes no
sense to write infinite loops - unless for a good reason.


-Panu Viljamaa

[Dmitry A. Kazakov]

Post by DBC User
I am interested in learning the difference between set (theory) and a
class.

In programming languages class is a set of types.

Post by DBC User
For example, if I have a class say Person and it has a specialised
class student and say sue is an instance of student.
Then as per set theory, Student is a subset of Person and Sue is
element of student/Person. I can see how instance and specilisation
can be represented in set theory. But I can not find a difference.
Could some one help me?

The class Person has the class Student as a subset. The type Person is an
element of the class Person. The type Student is an element of both the
class Person and the class Student.

Sue is a value of the type Student. It is not of the type Person, but it
can be transparently converted to the type Person.

[unknown]

using different names for the different context does not approach

"identity". maybe i am thinking that sets and class is about identity. i
had some time ag read a lawbok on these issues. from programming they use a
class to be the template for all instances of the class produced. the
pooling strategy is an analogy. when a new user signs onto the network, he
activates a new instance to use, within the group on the network. he is
able to communicate with the network as one of the group.

the class issue is known from taxonomy, which is something like genus and
species. and libraries use the classification for subject which are
referred to by their books. but a student is a person in that he breathes?
suppose we say that all people are learning, then who is the student. it is
not that far fetched to attach learning to the person. object relationships
in object programming are based on replication, not much on identity. the
shole computer is based on variations of the bits in a string of digits.


Oye como va
mi ritmo.
Bueno pa' goza,
Mulata

The only reasonable Engish translation would be "Listen how my rhythm goes.
Good to get your grove on, Mulata" with Mulata being a 'lovely' nickname to
a dark complected woman, possibly to whom the song was dedicated.


### Downloaded: 22/01/2003 16:37 - PST
#----------------------------------PLEASE
NOTE----------------------------------#
# This file is the author's own work and represents their interpretation of
the #
# song. You may only use this file for private study, scholarship, or
research. #
#---------------------------------------------------------------------------
----#

"Oye Como Va"
by Santana
off of Santana's Greatest Hits

as tabbed by Ryan Izzo
(CD time in parentheses)

h = hammer on p = pull off
b = bend r = release bend
\ = slide ~ = let ring

Intro:
e|--------7-8-10--7-------|
B|-10--10-----------8h10--|
G|------------------------| Repeat 4X
D|------------------------|
A|------------------------|
E|-(0:16)-----------------|

Spanish: Oye como va ....me lee mo weirdo peudo sa????? (I'm a white
boy)
English: Listen to how it goes... (someone help)

Solo 1:
e|-----------------------------------------------------------------|
B|-------8---8-7------------------------8---8-7--10----------------|
G|-----9---9------7----5h7-7p5--------9---9------------------------|
D|-7---------------------------7--7--------------------------------|
A|-----------------------------------------------------------------|
E|-(0:57)------------------------(1:01)----------------------------|

e|-----------------------------------------------------------------|
B|-------8---8-7----------------------8-10--8-7--10 b 13-------|
G|-----9---9------7--5h7-7p5--------9------------(slow bend)-------|
D|-7-------------------------7---10--------------------------------|
A|-----------------------------------------------------------------|
E|-(1:05)----------------------(1:08)------------------------------|

e|-8-8-5-5-8-5--8--5----5------------8-8-5-5-8-5---5---------------|
B|--------------------7-------------------------/7-----------------|
G|------------------------5h7-7p5---------------------7b8-5--------|
D|--------------------------------7--------------------------------|
A|-----------------------------------------------------------------|
E|-(1:12)--------------------------(1:16)--------------------------|

e|-8-8-5-5-8-5--8--5----5------------8-8-5-5-8-5---5~/12-----------|
B|--------------------7--------------------------7-----------------|
G|------------------------5h7-5------------------------------------|
D|------------------------------7p6--------------------------------|
A|-----------------------------------------------------------------|
E|-(1:19)--------------------------(1:23)--------------------------|

e|-8-5--8-5--8-5--8-5--8-5--8-5--8-5--8-5--------------------------|
B|-----------------------------------------------------------------|
G|-----------------------------------------5h7---5h7-7p5-----------|
D|-------------------------------------------------------7---------|
A|-----------------------------------------------------------------|
E|-(1:27)----------------------------------------------------------|

e|-----------------------------------------------------------------|
B|---------5---5-7---------------------5---5-7---------------------|
G|-5-555-5---5-----------------5-555-5---5-------------------------|
D|-(weird)---------4--5--6--7-------------------4--5--6--7---------|
A|-----------------------------------------------------------------|
E|-(1:34)----------------------(1:38)------------------------------|

e|-----------------------------------------------------------------|
B|---------5---5-7-------------------------------------------------|
G|-5-555-5---5-----------------------------------------------------|
D|------------------4--5--6--7-------------------------------------|
A|-----------------------------------------------------------------|
E|-(1:42)----------------------------------------------------------|

mostly keyboard and other junk here . I am not good with
chords so if someone could fill in this blank I would appreciate it.

Solo 2:
e|--5/12---8-8-5-5-8-5--8--5----5-------------8-8-5-5-8-5----------|
B|----------------------------7---------------------------7h10-----|
G|--------------------------------5h7-7p5--------------------------|
D|----------------------------------------7------------------------|
A|-----------------------------------------------------------------|
E|-(3:20)-------------------------------------(3:26)---------------|

e|-8-8-5-5-8-5--8--5----5------------8-8-5-5-8-5----5~/12----------|
B|--------------------7--------------------------/7----------------|
G|------------------------5h7-7p5----------------------------------|
D|--------------------------------7--------------------------------|
A|-----------------------------------------------------------------|
E|-(3:29)----------------------------(3:33)------------------------|

e|-17b18r17b18r17-12-/14--17---------------------------------------|
B|---------------------------15------------------------------------|
G|--------------------------------12b14---12-b14---12-b14---12-b14-|
D|-----------------------------------------------------------------|
A|-----------------------------------------------------------------|
E|-(3:37)------------------------(3:40)----------------------------|

e|-----------------------------------------------------------------|
B|-----------10----------------------------------------------------|
G|-12-b14-12----12-------------12-----------------------12/13------|
D|-----------------12-10----10-12-10----12/13---12/13---12/13------|
A|-----------------------12----------12----------------------------|
E|-(3:43)----------------------------------------------------------|

e|-----------------------------------------------------------------|
B|-----------------------------------------------------------------|
G|----------------12-----------------------------------------------|
D|-12/13-10----10-12-10---------10/12-12p10-------10-12-12p10-10-10|
A|----------12----------12--/12-10/12-12p10-12p10-10-12-12p10-10-10|
E|-(3:48)-----------------------(3:51)------12p10------------------|

e|-8-5--8-5--8-5--/12-5--8-5-8\5--8-5--88-5--8-5--8-5--8-5-8-5-----|
B|-----------------------------------------------------------------|
G|-----------------------------------------------------------------|
D|-----------------------------------------------------------------|
A|-----------------------------------------------------------------|
E|-(3:55)----------------------------------------------------------|

e|-8p5-8-8p5-8-5-8-5-----------------------------------------------|
B|-----------------------------------------------------------------|
G|-----------------------------------------------------------------|
D|-----------------------------------------------------------------|
A|-----------------------------------------------------------------|
E|-(4:03)----------------------------------------------------------|

I don't see too many Santana tabs so this should help.
I would love to hear any corrections, suggestions, or praises.

Ryan Izzo




Oye Como Va
by
Santana


Okay, for those who can't figure out the lyrics to
Oye Como Va by Santana, here they are with an english
translation too!!

Oye Como Va Hey How's it going
Mi ritmo My rythm
Bueno pa gosar It is fun to dance
Dudar No doubt

Oh I forgot to say that it is a wierd english
translation. It is like if you tell a joke in
spanish and then tell the english translation it is
not funny. So the way for it to make sense to those
who "No speka spanishio" it would be:

Hey how's it going
There is no doubt that my rythm is fun to dance.

--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

[H. S. Lahman]

Responding to User...

Post by DBC User
I am interested in learning the difference between set (theory) and a
class.
For example, if I have a class say Person and it has a specialised
class student and say sue is an instance of student.
Then as per set theory, Student is a subset of Person and Sue is
element of student/Person. I can see how instance and specilisation
can be represented in set theory. But I can not find a difference.
Could some one help me?

In OOA/D one deals with just class systems. A class is simply a set
whose members are objects. The class is unique because it is defined, in
turn, by a set of properties that all member objects possess.

In addition, an OO generalization in UML is just a Venn Diagram from set
theory in tree form. The dots are objects (Sue) and subclasses are
subsets (Student) of the root set (Person). The reason a tree form is
used in UML is because the subsets are defined in by sets of properties
and the tree format is convenient for enumerating the properties. (OO
inheritance is just a suite of rules for determining which properties a
given dot (object) has by "walking" the subset boundaries.)

This rather simple mapping to set theory is why OO generalization is
referred to as an is-a relationship. Sue is a Student and Sue is a
Person. So an OO generalization object reflects membership in both sets
(i.e., the object's properties are a union of the properties of all sets
in a direct line of ascent to the root superset). IOW, the object
instantiates the entire tree. That contrasts with Data Modeling where
each set in the tree can be instantiated independently (and always is in
an RDB).


*************
There is nothing wrong with me that could
not be cured by a capful of Drano.

H. S. Lahman
***@pathfindermda.com
Pathfinder Solutions
http://www.pathfindermda.com
blog: http://pathfinderpeople.blogs.com/hslahman
"Model-Based Translation: The Next Step in Agile Development". Email
***@pathfindermda.com for your copy.
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