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From: zuhair on 31 Oct 2009 15:33 Let me right the theory completely with its five axiom schemes: T is the set of all sentences entailed (from FOL with identity, membership and the primitive constant V) by the following non logical axioms. 1) Extensionality: For all z ( z e x <-> z e y ) -> x=y 2) Class Comprehension:if Phi is a formula that do not use V, and in which x is not free, then all closures of Exist x For all y ( y e x <-> (y e V & Phi) ) are axioms. 3) Set Comprehension: IF Phi(y,x1,...,xn) is a formula which do not use V, and in which y,x1,...,xn are its sole free variables, and in which s is not free, and if Q1,...,Qm are all sub-formulas of Phi in which y is free, and their parameters are subset of the parameters of Phi, then For all x1 e V,...,xn e V ( ~(Q1{y|Q1}& For all y ( Q1 -> ~yey )),..., ~(Qm{y|Qm}& For all y ( Qm -> ~yey )) -> Exist a set s for all y ( y e s <-> Phi(y,x1,...,xn ) ). are axioms. 4) Anti-foundation: Exist x: x e x 5) Transitive: For all x , y ( y e x & x e V -> y e V ). Theory definition finished/ Zuhair
From: zuhair on 31 Oct 2009 16:10 On Oct 31, 2:33 pm, zuhair <zaljo...(a)gmail.com> wrote: > Let me right the theory completely with its five axiom schemes: > > T is the set of all sentences entailed (from FOL with identity, > membership and the primitive constant V) by the following non logical > axioms. > > 1) Extensionality: For all z ( z e x <-> z e y ) -> x=y > > 2) Class Comprehension:if Phi is a formula that do not use V, and in > which x is not free, then all closures of > > Exist x For all y ( y e x <-> (y e V & Phi) ) > > are axioms. > > 3) Set Comprehension: IF Phi(y,x1,...,xn) is a formula which do not > use V, and in which y,x1,...,xn are its sole free variables, and in > which s is not free, and if Q1,...,Qm are all sub-formulas of Phi in > which y is free, and their parameters are subset of the parameters of > Phi, then > > For all x1 e V,...,xn e V ( > ~(Q1{y|Q1}& For all y ( Q1 -> ~yey )),..., > ~(Qm{y|Qm}& For all y ( Qm -> ~yey )) > > -> Exist a set s for all y ( y e s <-> Phi(y,x1,...,xn ) ). > > are axioms. > > 4) Anti-foundation: Exist x: x e x > > 5) Transitive: For all x , y ( y e x & x e V -> y e V ). > > Theory definition finished/ > > Zuhair Actually there is a lot of restrictions on set comprehension, like parameters being not in V and the formula not using V, I think with this theory this is not needed. Actually I do believe that we might dispense with the primitive constant V altogether, and present a theory in MK fashion with the restriction of not using paradoxical formulas. So we can have a theory in FOL with e and =. and define "set" as in Morse-Kelley set theory as an object that is a member of another object, in symbols: x is a set <-> Exist y ( x e y ) and have the axiom of Extensionality and the schema of class comprehension as in Morse-Kelley set theory. and then add the anti-foundation axiom of Exist x: x e x., and add the following set comprehension schema. 3) Set Comprehension: IF Phi is a formula in which at least y is free, and in which x is not free, and if Q1,...,Qm are all sub-formulas of Phi in which y is free, with no parameter in them other than those parameters in phi, then all closures of: ~(Q1{y|Q1}& For all y (Q1 -> ~yey))&...& ~(Qm{y|Qm}& For all y (Qm -> ~yey)) -> Exist a set x for all y (y e x <-> Phi). are axioms. I think this Morse-Kelley like theory would be sufficient for the quest of this theory. The same thing applies here, if we work with well founded sets then it seems that Morse-Kelley would be a sub-theory of this theory, if we work with all sets, then perhaps we can have a good theory dealing with universal sets,while at the same time having Morse-Kelley and thus ZF as a sub-theory of it. Zuhair
From: zuhair on 31 Oct 2009 17:08 On Oct 31, 3:10 pm, zuhair <zaljo...(a)yahoo.com> wrote: > On Oct 31, 2:33 pm, zuhair <zaljo...(a)gmail.com> wrote: > > > > > > > Let me right the theory completely with its five axiom schemes: > > > T is the set of all sentences entailed (from FOL with identity, > > membership and the primitive constant V) by the following non logical > > axioms. > > > 1) Extensionality: For all z ( z e x <-> z e y ) -> x=y > > > 2) Class Comprehension:if Phi is a formula that do not use V, and in > > which x is not free, then all closures of > > > Exist x For all y ( y e x <-> (y e V & Phi) ) > > > are axioms. > > > 3) Set Comprehension: IF Phi(y,x1,...,xn) is a formula which do not > > use V, and in which y,x1,...,xn are its sole free variables, and in > > which s is not free, and if Q1,...,Qm are all sub-formulas of Phi in > > which y is free, and their parameters are subset of the parameters of > > Phi, then > > > For all x1 e V,...,xn e V ( > > ~(Q1{y|Q1}& For all y ( Q1 -> ~yey )),..., > > ~(Qm{y|Qm}& For all y ( Qm -> ~yey )) > > > -> Exist a set s for all y ( y e s <-> Phi(y,x1,...,xn ) ). > > > are axioms. > > > 4) Anti-foundation: Exist x: x e x > > > 5) Transitive: For all x , y ( y e x & x e V -> y e V ). > > > Theory definition finished/ > > > Zuhair > > Actually there is a lot of restrictions on set comprehension, like > parameters being not in V and the formula not using V, I think with > this theory this is not needed. Actually I do believe that we might > dispense with the primitive constant V altogether, and present a > theory in MK fashion with the restriction of not using paradoxical > formulas. > > So we can have a theory in FOL with e and =. and define "set" as in > Morse-Kelley set theory as an object that is a member of another > object, in symbols: x is a set <-> Exist y ( x e y ) > and have the axiom of Extensionality and the schema of class > comprehension as in Morse-Kelley set theory. and then add the > anti-foundation axiom of Exist x: x e x., and add the following set > comprehension schema. > > 3) Set Comprehension: IF Phi is a formula in which at least y is free, > and in which x is not free, and if Q1,...,Qm are all > sub-formulas of Phi in which y is free, with no parameter in them > other than those parameters in phi, then all closures of: > > ~(Q1{y|Q1}& For all y (Q1 -> ~yey))&...& > ~(Qm{y|Qm}& For all y (Qm -> ~yey)) > > -> Exist a set x for all y (y e x <-> Phi). > > are axioms. > > I think this Morse-Kelley like theory would be sufficient for the > quest of this theory. > > The same thing applies here, if we work with well founded sets then it > seems that Morse-Kelley would be a sub-theory of this theory, if we > work with all sets, then perhaps we can have a good theory dealing > with universal sets,while at the same time having Morse-Kelley and > thus ZF as a sub-theory of it. > > Zuhair I do think now that this theory is weaker than ZF or MK, since it forbid us from the use of formulas like x is ordinal, etc... in separation. Zuhair
From: Charlie-Boo on 1 Nov 2009 07:02 > > Zuhair > > I do think now that this theory is weaker than ZF or MK, since it > forbid us from the use of formulas like x is ordinal, etc... in > separation. No it isn't and doesn't - why do you think that? It is diagonalization. It is merely a formalization of diagonalization. -~P/P We cannot represent the negation of the system within the system. That is the only axiom needed for negative results. E.g. -~SE/SE There is no set of all sets that do not contain themselves. -~YES/YES The set of programs that don't halt Yes is not r.e. -~TS/TS We cannot define truth in English using English. where SE, YES and TS are standard i.e. SE(a,b) "b is an element of a." YES(a,b) "Turing Machine a with b as input halts yes." TS(a,b) "English sentence a with noun phrase b substituted for its pronouns is true." This provides the only universal justification of its resolution of the paradoxes (Russell and Liar above) thus satisfying the standard criteria for correctness. C-B > Zuhair "Zuhair"? It sounds like one of those African natives. Do you have a bone sticking through your nose?
From: Marshall on 2 Nov 2009 09:33
On Nov 2, 4:43 am, Charlie-Boo <shymath...(a)gmail.com> wrote: > On Nov 2, 6:23 am, "Jesse F. Hughes" <je...(a)phiwumbda.org> wrote: > > > Charlie-Boo <shymath...(a)gmail.com> writes: > > > "Zuhair"? It sounds like one of those African natives. Do you have > > > a bone sticking through your nose? > > > Congrats, Charlie! A new low! > > Low? What is low about African culture? > > http://images.google.com/imgres?imgurl=http://farm3.static.flickr.com.... Unfortunately for your argument Papua New Guinea is not in Africa. Marshall |