I will answer your questions out of order:
This is not my definiton for at least two reasons:
1) Subset is not the same as proper subset.
2) You ignored the term "cannot be but |B| < |A|".
1)It's not my fault that you are not using non-standard terms. You have not defined "proper subset". I defined subset, and used it accordingly. Please give your definition of subset and proper subset. Please then explain the differences.
2) Yes I have. "Cannot be but" is the same as "then". Example: If you continue to use standard terms in non-standard ways, you cannot be but misunderstood by 99.9% of the posters. If you use too many words when few will do, you cannot but be looked upon as being unclear.
Definition 2: Set A is called finite if the cardinal of proper subset B of A cannot be but |B| < |A|.
Definition 2 says that A is finite if its proper subset cannot be but |B| < |A|
What is not clear here? I do not think that by definition 2 we can conclude that property not-X is non-finite.
What do you mean by property? We are only talking about if a set is either finite or non-finite based only on cardinality, not "not-X". In your quoted messages contained in this post, your definitions of #2 and #3 only talk about finite and non-finite.
Let us try this version of definition 3:
Definition 3: Set A is called non-finite if the cardinal of proper subset B of A can be (|B| < |A|) AND (|B| = |A|).
Using an example, how can 3 be equal and less than 4? Cardinality does not care about the members of a set, it just cares about how many, and then we compare those two values, using def #3, to see if set A is non-finite.
Little 10 Toes,
If we observe a non-local element, its value can be in more than a one relation w.r.t another element.
But this is not the case here.
Then why bring it up?
In this case I am trying to define the difference between finite and non-finite sets, where each member is local (can be distinguished from another member by using only one relation).
You have not defined "local". Defs #2 and Def #3 are only talking about cardinality, sets, and subsets. They don't mention members at all. Why are you bringing up members when you only care about defining finite and non-finite sets? One of your posts mention that want to define sets, but do not mention members. In fact, you posted this before I posted my message, remember?
(quoted message that does not show when I quote this message)
"Cannot be but ..." is an understatement of "must be ..." and I prefer to use understatements.
(another quoted message that does not show when I quote this message)
It will be come later.
At this stage I wish to clearly distinguish between finite and non-finite sets.
Please answer to
http://www.internationalskeptics.com/forums/showpost.php?p=4236183&postcount=896 .
Let's continue with the original post:
Let us use the notion of proper subset in order to distinguish between finite and non-finite sets as follows:
Definition 3: If A is a set and B is some arbitrary proper subset of A, then if |B| cannot be but |B| < |A|, then A is finite.
If we can use definition 3 in order to conclude that anything that does not satisfy it, must be a non-finite set, then definition 3 is enough to distinguish between finite and non-finite sets.
What do you think?
Well, it woud be nice to use the notion, but since you have a history of springing new words, or using common words but with different standard definitions, I can't since you have not defined "proper subset". In addition, you did not dispute my example of set A being all positive whole even numbers, and set B being all positive whole even numbers evenly divisible by five. Most mathematicians would say both sets are infinite, but by using def #2, set A is finite.
I think you are overthinking things. Would you agree to the following definitions of the following terms:
- CardinalityWP: "In mathematics, the cardinality of a set is a measure of the "number of elements of the set". For example, the set A = {1, 2, 3} contains 3 elements, and therefore A has a cardinality of 3." Using the example set shown, I will use the notation |A| = 3 .
- SubsetWP: "In mathematics, especially in set theory, a set A is a subset of a set B if A is "contained" inside B. Notice that A and B may coincide."
- Infinite: something that has no end or begining; something that cannot have a value attached to; unmeasurable/uncountable; unquantifiable. Example, the smallest/largest number; in geometry, a line. SynonymWP: non-finite.
- Finite: something that does have an end; can have a value attached to; measurable/countable; practical; quantifiable. Example: the number of coins in my pocket, the number of grains of sand on a beach; in geometry, a line segment
- "Cannot be but": synonym of "then"
Do you agree to these definitions to the words?
If you only think about sets and subsets, and use "standard" mathematical "grammer", my definitions are the same as yours, just cleaner. Can you give me your definition of subset, proper subset, and the difference between the two without using examples until requested?