d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin Fin Fin Fin . . . A A A A F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin . . . A F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin . . . A F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin . . . A F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin . . . A F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact P ( N ) \ οΏ½
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . A F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . β’ β’ β’ A a F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . β’ β’ β’ A a F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c | A \ οΏ½ n O n | < d
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . β’ β’ β’ A a F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c | A \ οΏ½ n O n | < d β A \ οΏ½ n O n is Menger
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . β’ β’ β’ A a F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c | A \ οΏ½ n O n | < d β A \ οΏ½ n O n is Menger
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . β’ β’ β’ A a F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c | A \ οΏ½ n O n | < d β A \ οΏ½ n O n is Menger
d -unbounded sets A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β is d -unbounded β A βͺ Fin is Menger Fin c β’ β’ β’ . . . β’ β’ β’ A a F 1 βͺ { O 1 } β O 1 F 2 βͺ { O 2 } β O 2 F 3 βͺ { O 3 } β O 3 Fin β οΏ½ n O n n O n β [ N ] β is compact, β c β [ N ] β P ( N ) \ οΏ½ P ( N ) \ οΏ½ n O n β€ c | A \ οΏ½ n O n | < d β A \ οΏ½ n O n is Menger A βͺ Fin is Menger
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger Corollary cf( d ) < d β β Menger X , Y β P ( N ) , X Γ Y is not Menger
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger Corollary cf( d ) < d β β Menger X , Y β P ( N ) , X Γ Y is not Menger β cf( d )-unbounded X β [ N ] β , | X | = cf( d )
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger Corollary cf( d ) < d β β Menger X , Y β P ( N ) , X Γ Y is not Menger β cf( d )-unbounded X β [ N ] β , | X | = cf( d ) | X | = cf( d ) < d β X is Menger
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger Corollary cf( d ) < d β β Menger X , Y β P ( N ) , X Γ Y is not Menger β cf( d )-unbounded X β [ N ] β , | X | = cf( d ) | X | = cf( d ) < d β X is Menger β Menger Y β [ N ] β , X Γ Y is not Menger
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) Fin [ N ] β , β cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin [ N ] β , β [ N ] β , β cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin A βͺ Fin is Menger [ N ] β , β [ N ] β , β cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin A βͺ Fin is Menger Ο : P ( N ) β P ( N ), Ο ( a ) = a c = a β N [ N ] β , β [ N ] β , β cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin A βͺ Fin is Menger Ο : P ( N ) β P ( N ), Ο ( a ) = a c = a β N X = Ο [ A βͺ Fin ] = { a c : a β A } βͺ cFin β [ N ] β [ N ] β , β [ N ] β , β cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin Fin A βͺ Fin is Menger Ο : P ( N ) β P ( N ), Ο ( a ) = a c = a β N X = Ο [ A βͺ Fin ] = { a c : a β A } βͺ cFin β [ N ] β [ N ] β , β [ N ] β , β [ N ] β , β cFin cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin Fin A βͺ Fin is Menger Ο : P ( N ) β P ( N ), Ο ( a ) = a c = a β N X = Ο [ A βͺ Fin ] = { a c : a β A } βͺ cFin β [ N ] β [ N ] β , β [ N ] β , β [ N ] β , β d -unbounded { a c : a β A } β X cFin cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger P ( N ) d β€ r β β bi- d -unbounded A β [ N ] β , β Fin Fin Fin A βͺ Fin is Menger Ο : P ( N ) β P ( N ), Ο ( a ) = a c = a β N X = Ο [ A βͺ Fin ] = { a c : a β A } βͺ cFin β [ N ] β [ N ] β , β [ N ] β , β [ N ] β , β d -unbounded { a c : a β A } β X β Menger Y β P ( N ), X Γ Y is not Menger cFin cFin
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger Productivity of Menger MA Cohen Random Sacks Hechler Laver Mathias Miller
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger Productivity of Menger MA Cohen Random Sacks Hechler Laver Mathias Miller
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger Productivity of Menger MA Cohen Random Sacks Hechler Laver Mathias Miller ?
Main results A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d A β [ N ] β , β is bi- d -unbounded if A and { a c : a β A } are d -unbounded r : min card of A β [ N ] β , there is no r β [ N ] β s.t. for all a β A r β© a and r \ a are infinite Corollary d β€ r β β Menger X , Y β P ( N ) , X Γ Y is not Menger Productivity of Menger MA Cohen Random Sacks Hechler Laver Mathias Miller ? Theorem ? (Zdomskyy) In the Miller model Menger is productive
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x /
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X F 1 β O 1
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . F 1 β O 1
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . F 1 β O 1
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . F 1 β O 1 F 2 β O 2 F 3 β O 3
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . F 1 β O 1 F 2 β O 2 F 3 β O 3
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . F 1 β O 1 F 2 β O 2 F 3 β O 3
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . β’ x F 1 β O 1 F 2 β O 2 F 3 β O 3
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . β’ x F 1 β O 1 F 2 β O 2 F 3 β O 3 Hurewicz β Menger
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . β’ x F 1 β O 1 F 2 β O 2 F 3 β O 3 Ο -compact β Hurewicz β Menger
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . β’ x F 1 β O 1 F 2 β O 2 F 3 β O 3 Ο -compact β Hurewicz β Menger Aurichi, Tall ( d = β΅ 1 ): metrizable productively LindelΒ¨ of β Hurewicz
The Hurewicz property Hurewiczβs property: for every sequence of open covers O 1 , O 2 , . . . of X there are finite F 1 β O 1 , F 2 β O 2 , . . . such that for each x β X , the set β οΏ½ F n } is finite { n β N : x / X X X X . . . β’ x F 1 β O 1 F 2 β O 2 F 3 β O 3 Ο -compact β Hurewicz β Menger Aurichi, Tall ( d = β΅ 1 ): metrizable productively LindelΒ¨ of β Hurewicz Sz (ZFC): separable productively paracompact β Hurewicz
Hurewicz meets combinatorics β’ y β’ x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ β’ β’ β’ β’ β’ β’ β’ x β’ β’ β’ β’ β’
Hurewicz meets combinatorics β’ β’ β’ y x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ x β’ β’ y β€ β x if x οΏ½β€ β y β’ β’ β’ β’ β’ β’ β’ β’ β’
Hurewicz meets combinatorics β’ c β’ x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ β’ y β€ β x if x οΏ½β€ β y β’ β’ β’ y Y is bounded if β c β [ N ] β β y β Y y β€ β c β’ β’ β’ β’ β’ β’ β’ β’
Hurewicz meets combinatorics β’ c β’ x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ β’ y β€ β x if x οΏ½β€ β y β’ β’ β’ y Y is bounded if β c β [ N ] β β y β Y y β€ β c β’ β’ β’ β’ β’ b : minimal cardinality of an unbounded set β’ β’ β’
Hurewicz meets combinatorics β’ c β’ x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ β’ y β€ β x if x οΏ½β€ β y β’ β’ β’ y Y is bounded if β c β [ N ] β β y β Y y β€ β c β’ β’ β’ β’ β’ b : minimal cardinality of an unbounded set β’ β’ β’ Theorem (Hurewicz) Assume that X is LindelΒ¨ of and zero-dimensional X is Hurewicz β continuous image of X into [ N ] β is unbounded
Hurewicz meets combinatorics β’ c β’ x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ β’ y β€ β x if x οΏ½β€ β y β’ β’ β’ y Y is bounded if β c β [ N ] β β y β Y y β€ β c β’ β’ β’ β’ β’ b : minimal cardinality of an unbounded set β’ β’ β’ Theorem (Hurewicz) Assume that X is LindelΒ¨ of and zero-dimensional X is Hurewicz β continuous image of X into [ N ] β is unbounded
Hurewicz meets combinatorics β’ c β’ x β€ β y if x ( n ) β€ y ( n ) for almost all n β’ β’ β’ y β€ β x if x οΏ½β€ β y β’ β’ β’ y Y is bounded if β c β [ N ] β β y β Y y β€ β c β’ β’ β’ β’ β’ b : minimal cardinality of an unbounded set β’ β’ β’ Theorem (Hurewicz) Assume that X is LindelΒ¨ of and zero-dimensional X is Hurewicz β continuous image of X into [ N ] β is unbounded A LindelΒ¨ of X with | X | < b is Hurewicz An unbounded X β [ N ] β is not Hurewicz
Main theorem again A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger
Main theorem again A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger Y = A βͺ Fin , A is d -unbounded Fin c β’ β’ β’ β’ β’ β’ A a
Main theorem again A β [ N ] β is d -unbounded if | A | β₯ d and β c β [ N ] β |{ a β A : a β€ c }| < d Theorem (Sz, Tsaban) If X β [ N ] β contains a d -unbounded set or a cf( d )-unbounded set, then there is a Menger Y β P ( N ), X Γ Y is not Menger Y = A βͺ Fin , A is d -unbounded Fin c β’ β’ β’ β’ β’ β’ A a Tsaban, Zdomskyy: H is Hurewicz and hereditarily LindelΒ¨ of β H Γ Y is Menger
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz Asm X prod Menger, X Γ H not Hurewicz
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz Asm X prod Menger, X Γ H not Hurewicz X Γ H β Y β [ N ] β unbounded
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ s Ξ± ( b = d ) β’ β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ β’ β’ s Ξ² β’ β’ β’ β’ β’ β’
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± s Ξ± β€ β y Ξ± β Y β’ β’ β’ β’
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz β’ Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ β’ s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ s Ξ± β€ β y Ξ± β Y y Ξ± β’ β’ β’ β’ β’ β’ β’
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz β’ Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ β’ s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ s Ξ± β€ β y Ξ± β Y y Ξ± β’ β’ β’ β’ d -unbounded { y Ξ± : Ξ± < b } β Y β’ β’ β’
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz β’ Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ β’ s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ s Ξ± β€ β y Ξ± β Y y Ξ± β’ β’ β’ β’ d -unbounded { y Ξ± : Ξ± < b } β Y β’ β’ β Menger M β P ( N ), Y Γ M not Menger β’
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz β’ Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ β’ s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ s Ξ± β€ β y Ξ± β Y y Ξ± β’ β’ β’ β’ d -unbounded { y Ξ± : Ξ± < b } β Y β’ β’ β Menger M β P ( N ), Y Γ M not Menger β’ ( X Γ H ) Γ M β Y Γ M , ( X Γ H ) Γ M not Menger
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz β’ Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ β’ s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ s Ξ± β€ β y Ξ± β Y y Ξ± β’ β’ β’ β’ d -unbounded { y Ξ± : Ξ± < b } β Y β’ β’ β Menger M β P ( N ), Y Γ M not Menger β’ ( X Γ H ) Γ M β Y Γ M , ( X Γ H ) Γ M not Menger H Γ M is Menger, X Γ ( H Γ M ) is Menger
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz β’ Asm X prod Menger, X Γ H not Hurewicz β’ β’ X Γ H β Y β [ N ] β unbounded β’ β’ s Ξ± ( b = d ) β’ β’ β dominating { s Ξ± : Ξ± < b } , s Ξ² β€ β s Ξ± , Ξ² β€ Ξ± β’ β’ s Ξ± β€ β y Ξ± β Y y Ξ± β’ β’ β’ β’ d -unbounded { y Ξ± : Ξ± < b } β Y β’ β’ β Menger M β P ( N ), Y Γ M not Menger β’ ( X Γ H ) Γ M β Y Γ M , ( X Γ H ) Γ M not Menger H Γ M is Menger, X Γ ( H Γ M ) is Menger
Productivity of Menger and Hurewicz X is productively Menger if for each Menger M , X Γ M is Menger Theorem (Sz, Tsaban) b = d , hereditarily LindelΒ¨ of spaces productively Menger β productively Hurewicz What about general spaces?
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