1. ## General Proof Question

In the proofs that I submitted with my assignments, I used the logical symbol for because (the therefore symbol upside down) and the marker crossed it out and replaced it with "since". Why?

2. Originally Posted by Noxide
In the proofs that I submitted with my assignments, I used the logical symbol for because (the therefore symbol upside down) and the marker crossed it out and replaced it with "since". Why?
Did the penalise you for it?

If not it is their personal stylistic preference (I prefer writing such things in words myself)

CB

3. I would complain. "Because" and "Since" have the same meaning...

4. Originally Posted by Prove It
I would complain. "Because" and "Since" have the same meaning...
Yes, but using a word as opposed to a symbol is the substance of the change.

CB

5. The symbols $\therefore$ and $\because$ are much less known than, e.g., $\Rightarrow$. My opinion is that unless you know that the person reading your proof is aware of them and does not mind them, you should not use them. Or, at least, you should make a note explaining what these symbols mean.

6. Originally Posted by emakarov
The symbols $\therefore$ and $\because$ are much less known than, e.g., $\Rightarrow$. My opinion is that unless you know that the person reading your proof is aware of them and does not mind them, you should not use them. Or, at least, you should make a note explaining what these symbols mean.
Or the person reading could look them up... There is such a thing as reciprocal responsibility...

7. Originally Posted by Prove It
Or the person reading could look them up... There is such a thing as reciprocal responsibility...
Why use a notation when the word/s is/are clearer? Are we after obscurity for its own sake?

The purpose of a proof is to communicate an idea not to raise barriers to communication.

"Or the person reading could look them up..." or they could decide that we are so arrogant we are not worth reading.

The vast majority of students passing through maths courses are not destined to be mathematicians, in which case they should be taught in a manner that does not raise barriers against understanding. You are not going to make them mathematicians by making them jump through inappropriate notational hoops.

CB

8. Originally Posted by CaptainBlack
Why use a notation when the word/s is/are clearer? Are we after obscurity for its own sake?

The purpose of a proof is to communicate an idea not to raise barriers to communication.

"Or the person reading could look them up..." or they could decide that we are so arrogant we are not worth reading.

The vast majority of students passing through maths courses are not destined to be mathematicians, in which case they should be taught in a manner that does not raise barriers against understanding. You are not going to make them mathematicians by making them jump through inappropriate notational hoops.

CB
Except this is not a case of a a teacher using inappropriate notation when trying to teach a student, it's a case of a student using appropriate notation in work that was handed to a teacher. The teacher should not be discouraging the student from using appropriate notation because of his/her own inadequacies, the teacher should be viewing this as something new he/she has learnt.

9. Originally Posted by Prove It
Except this is not a case of a a teacher using inappropriate notation when trying to teach a student, it's a case of a student using appropriate notation in work that was handed to a teacher. The teacher should not be discouraging the student from using appropriate notation because of his/her own inadequacies, the teacher should be viewing this as something new he/she has learnt.
It is not a matter of inadequacy it is a matter of clarity.

CB

10. I always thought symbols were much more clear than words (e.g. logical "exclusive or" symbol versus writing the word "or"). I was not penalized, so it is perhaps a stylistic preference of the marker as the word "since" exactly means "because" when it is used as a conjunction.