Turn on thread page Beta
    • Wiki Support Team
    Offline

    14
    ReputationRep:
    Wiki Support Team
    (Original post by LJoll)
    Well one of them implies that two things are exactly the same and the other says that one things can only be true if the other is true, but does not necessitate any specific relationship between the properties of the two things.
    That's not quite what iff says. A iff B means that "A is true whenever B is true, and false whenever B is false, and vice-versa". That sounds very much like the sort of equivalence that "equals" also indicates to me. On the contrary; "A iff B" indicates that A and B are dependent to the point of having all the same properties.
    Offline

    0
    ReputationRep:
    (Original post by generalebriety)
    That's not quite what iff says. A iff B means that "A is true whenever B is true, and false whenever B is false, and vice-versa". That sounds very much like the sort of equivalence that "equals" also indicates to me. On the contrary; "A iff B" indicates that A and B are dependent to the point of having all the same properties.
    Yeah, that was a really lazy definition I gave.

    I think the main difference is that "A iff B" doesn't necessitate any correspondence of their properties. "=" does.
    • Thread Starter
    Offline

    14
    If anyone still cares, seven months later, about this question, my new lecturer has (rather promptly) provided an answer to this question. He explained that the difference is this: <-> is a propositional connective between two sentences, but = is a binary predicate between two objects. So, for our example, 2+2=4 because 2+2 is an object (or, rather, an object formed from a function symbol acting on two objects), and 4 is an object, but 2+2=4 is a sentence (because a sentence must have both objects and predicates - in this case the predicate is =).
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 5, 2009

University open days

  • Heriot-Watt University
    School of Textiles and Design Undergraduate
    Fri, 16 Nov '18
  • University of Roehampton
    All departments Undergraduate
    Sat, 17 Nov '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 17 Nov '18
Poll
Black Friday: Yay or Nay?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Equations

Best calculators for A level Maths

Tips on which model to get

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.