an update on the classification program of maximal ideals
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An update on the classification program of (maximal) ideals of algebras of operators on Banach spaces: the cases of Tsirelson and Schreier spaces . Tomasz Kania Academy of Sciences of the Czech Republic, Praha Madrid, 12.09.2019 joint work with


  1. An update on the classification program of (maximal) ideals of algebras of operators on Banach spaces: the cases of Tsirelson and Schreier spaces . Tomasz Kania Academy of Sciences of the Czech Republic, Praha Madrid, 12.09.2019 joint work with K. Beanland & N. J. Laustsen 1

  2. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. 2

  3. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). 2

  4. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: 2

  5. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: ◮ 0 ֒ → K ( X ) ֒ → B ( X ) , where X = c 0 or X = ℓ p for p ∈ [ 1 , ∞ ) . 2

  6. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: ◮ 0 ֒ → K ( X ) ֒ → B ( X ) , where X = c 0 or X = ℓ p for p ∈ [ 1 , ∞ ) . ◮ 0 ֒ → X ℵ 0 ( X ) ֒ → X ℵ 1 ( X ) ֒ → K ( X ) ֒ → . . . ֒ → B ( X ) , where X = c 0 (Γ) or X = ℓ p (Γ) for p ∈ [ 1 , ∞ ) and any set Γ ; X λ ( X ) ideal of ops having range of density at most λ . 2

  7. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: ◮ 0 ֒ → K ( X ) ֒ → B ( X ) , where X = c 0 or X = ℓ p for p ∈ [ 1 , ∞ ) . ◮ 0 ֒ → X ℵ 0 ( X ) ֒ → X ℵ 1 ( X ) ֒ → K ( X ) ֒ → . . . ֒ → B ( X ) , where X = c 0 (Γ) or X = ℓ p (Γ) for p ∈ [ 1 , ∞ ) and any set Γ ; X λ ( X ) ideal of ops having range of density at most λ . ◮ c 0 - and ℓ 1 -sums of ℓ n 2 as n → ∞ (Laustsen–Loy–Read, Laustsen–Schlumprecht–Zsák). 2

  8. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: ◮ 0 ֒ → K ( X ) ֒ → B ( X ) , where X = c 0 or X = ℓ p for p ∈ [ 1 , ∞ ) . ◮ 0 ֒ → X ℵ 0 ( X ) ֒ → X ℵ 1 ( X ) ֒ → K ( X ) ֒ → . . . ֒ → B ( X ) , where X = c 0 (Γ) or X = ℓ p (Γ) for p ∈ [ 1 , ∞ ) and any set Γ ; X λ ( X ) ideal of ops having range of density at most λ . ◮ c 0 - and ℓ 1 -sums of ℓ n 2 as n → ∞ (Laustsen–Loy–Read, Laustsen–Schlumprecht–Zsák). ◮ Koszmider’s C ( K ) -space from an AD family that exists under CH mentioned by Jesús on Tuesday. 2

  9. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: ◮ 0 ֒ → K ( X ) ֒ → B ( X ) , where X = c 0 or X = ℓ p for p ∈ [ 1 , ∞ ) . ◮ 0 ֒ → X ℵ 0 ( X ) ֒ → X ℵ 1 ( X ) ֒ → K ( X ) ֒ → . . . ֒ → B ( X ) , where X = c 0 (Γ) or X = ℓ p (Γ) for p ∈ [ 1 , ∞ ) and any set Γ ; X λ ( X ) ideal of ops having range of density at most λ . ◮ c 0 - and ℓ 1 -sums of ℓ n 2 as n → ∞ (Laustsen–Loy–Read, Laustsen–Schlumprecht–Zsák). ◮ Koszmider’s C ( K ) -space from an AD family that exists under CH mentioned by Jesús on Tuesday. ◮ Argyros–Haydon’s scalar-plus-compact space, sums of finitely many incomparable copies thereof, some variants due to Tarbard and further variants (Motakis–Puglisi–Zisimopoulou). 2

  10. Overview B ( X ) the Banach algebra of all bdd ops on a B. space X . Goal: to understand the lattice of closed ideals ( ∼ = representations) of B ( X ) . This is an isomorphic problem due to Eidelheit’s thm (1940). X ∼ ⇒ B ( X ) ∼ = Y as B. spaces ⇐ = B ( Y ) as B. algebras. Full classification exists for: ◮ 0 ֒ → K ( ℓ 2 ) ֒ → B ( ℓ 2 ) (Calkin, 1940). ◮ other classical spaces: ◮ 0 ֒ → K ( X ) ֒ → B ( X ) , where X = c 0 or X = ℓ p for p ∈ [ 1 , ∞ ) . ◮ 0 ֒ → X ℵ 0 ( X ) ֒ → X ℵ 1 ( X ) ֒ → K ( X ) ֒ → . . . ֒ → B ( X ) , where X = c 0 (Γ) or X = ℓ p (Γ) for p ∈ [ 1 , ∞ ) and any set Γ ; X λ ( X ) ideal of ops having range of density at most λ . ◮ c 0 - and ℓ 1 -sums of ℓ n 2 as n → ∞ (Laustsen–Loy–Read, Laustsen–Schlumprecht–Zsák). ◮ Koszmider’s C ( K ) -space from an AD family that exists under CH mentioned by Jesús on Tuesday. ◮ Argyros–Haydon’s scalar-plus-compact space, sums of finitely many incomparable copies thereof, some variants due to Tarbard and further variants (Motakis–Puglisi–Zisimopoulou). ◮ Z = X AH ⊕ suitably constructed subspace (K.–Laustsen). 2

  11. Maximal ideals A perspective . 3

  12. Maximal ideals A perspective . B ( Z ) has precisely two maximal ideals. ֒ → → M 1 ֒ 0 ֒ → K ( Z ) ֒ → E ( Z ) B ( Z ) → ֒ → ֒ M 2 3

  13. Maximal ideals A perspective . B ( Z ) has precisely two maximal ideals. ֒ → → M 1 ֒ 0 ֒ → K ( Z ) ֒ → E ( Z ) B ( Z ) → ֒ → ֒ M 2 This behaviour is rather rare. M X = { T ∈ B ( X ): I X � = ATB ( A , B ∈ B ( X )) } is the unique maximal ideal of B ( X ) ⇐ ⇒ M X closed under addition. 3

  14. Maximal ideals A perspective . B ( Z ) has precisely two maximal ideals. ֒ → → M 1 ֒ 0 ֒ → K ( Z ) ֒ → E ( Z ) B ( Z ) → ֒ → ֒ M 2 This behaviour is rather rare. M X = { T ∈ B ( X ): I X � = ATB ( A , B ∈ B ( X )) } is the unique maximal ideal of B ( X ) ⇐ ⇒ M X closed under addition. ◮ c 0 , ℓ p (here p = ∞ is included, btw. ℓ ∞ ∼ = L ∞ ); ◮ L p [ 0 , 1 ] for p ∈ [ 1 , ∞ ] . ◮ c 0 (Γ) , ℓ p (Γ) for p ∈ [ 1 , ∞ ) ◮ ℓ ∞ / c 0 , ℓ c ∞ (Γ) for any set Γ (but not every L ∞ ( µ ) is in this class!) ◮ c 0 - and ℓ p -sums of ℓ n 2 s or ℓ n ∞ s as well as more general sums. ◮ Lorentz sequence spaces determined by a decreasing, non-summable sequence and p ∈ [ 1 , ∞ ) . ◮ certain Orlicz spaces. ◮ C [ 0 , 1 ] , C [ 0 , ω ω ] , C [ 0 , ω 1 ] , and the list goes on. 3

  15. Tsirelson space revisited (Figiel–Johnson) Put a norm on c 00 : � � � x � ℓ ∞ , 1 � � x � T = max 2 sup � N i x � T i where the sup runs over j ∈ N and all finite sequences of sets N 1 < · · · < N j in N with j � min N 1 . 4

  16. Tsirelson space revisited (Figiel–Johnson) Put a norm on c 00 : � � � x � ℓ ∞ , 1 � � x � T = max 2 sup � N i x � T i where the sup runs over j ∈ N and all finite sequences of sets N 1 < · · · < N j in N with j � min N 1 . ◮ The standard u.v.b. ( t n ) ∞ n = 1 of T is 1-unconditional. 4

  17. Tsirelson space revisited (Figiel–Johnson) Put a norm on c 00 : � � � x � ℓ ∞ , 1 � � x � T = max 2 sup � N i x � T i where the sup runs over j ∈ N and all finite sequences of sets N 1 < · · · < N j in N with j � min N 1 . ◮ The standard u.v.b. ( t n ) ∞ n = 1 of T is 1-unconditional. ◮ For a space with an unconditional basis and N ⊂ N we call the ideal � P N � generated by the associated basis projection P N spatial 4

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