It depends what you mean by "necessary". There is a choice of different systems for (classical) predicate logic, but they all give the same results.
Universal introduction is certainly a valid principle in predicate logic, so the question is: Does universal introduction have to be one of the basic rules of the system?
The answer is no. It can be a derived principle. It is even possible to introduce "for all" as a derived symbol, and only have "there exists" in the basic system. The basic system would have a couple of rules controlling "there exists", and from these rules universal introduction would be a derived principle.
vivendi universal a french company
Universal Exports.
i think there nearly 10 banks which are universal banks
From the company that built your universal remote. Check their website.
Universal studios is a very big studio with rides movies and shows
SAREE MAKDISI has written: 'INTRODUCTION : UNIVERSAL EMPIRE'
Richard Turner has written: 'A new and easy introduction to universal geography'
J. R. Senft has written: 'An introduction to Stirling engines' -- subject(s): Stirling engines 'On weak automorphisms of universal algebras' -- subject(s): Algebra, Universal, Universal Algebra
Iodisation of salt is necessary because iodine deficiency lead to idiocy.
Forgive me, my French is a little rusty, but she says - "Greetings all. This is an introduction to a new space, a new era, a new sound. Welcome, you're about to enter Universal Mind Control"
Janet Anne Allison has written: 'A query facility for a universal relation database' 'Introduction to Windows 3.1'
State the theme, back up your statement with evidence, then explain why it is universal.
Roman Numerals are essential for simple counting, a universal counting method as well.
To rationalize the units on both sides of the equation, E= -GmM/r, e.g if feet is used as the unit of distance r then the Constant G would have a different value.
The effect of changing velocity can be eliminated by phasin the hookes joint Akray
Juha Korhonen has written: 'Introduction to 3G mobile communications' -- subject(s): Mobile communication systems, Universal Mobile Telecommunications System, Wireless communication systems
A universal hood release cable will work on the Ford Explorer if one is purchased that says it can be used on full size pickups and SUVs. The cable can be adjusted for length if that is necessary for the cable to fit properly.