The GATE Grind

GATE Functional Analysis: Bounded Linear Operators and Duality – Previous Year Questions

15 GATE previous year questions on Bounded Linear Operators and Duality (Functional Analysis, Mathematics) with answers and explanations, from every paper.

  1. GATE 2021 MA Q19 (1 mark, Multiple choice) – For an orthonormal basis (e n) of a complex Hilbert space H: P:there is a bounded linear f:H→ℂ with f(e n)=1/n. Q:there is a bounded linear g:H→ℂ with…
  2. GATE 2021 MA Q44 (2 marks, Multiple choice) – On C[0,1] with supremum norm define (Tf)(x)=∫₀ˣx f(t)dt. Let R(T) be its range. P:T is bounded linear. Q:T⁻¹:R(T)→C[0,1] exists and is bounded. Choose…
  3. GATE 2021 MA Q45 (2 marks, Multiple choice) – Let ℓ¹ have its usual norm and X=x∈ℓ¹:Σₙ₌₁∞n x(n) <∞. Define T:X→ℓ¹ by (Tx)(n)=nx(n), using on X the inherited ℓ¹ norm. Which holds?
  4. GATE 2022 MA Q43 (2 marks, Multiple choice) – X,Y,Z are Banach spaces, T:X→Y linear, and S:Y→Z bounded linear and injective. If S∘T is bounded, which must hold?
  5. GATE 2022 MA Q51 (2 marks, Multiple select) – For a>0 define D a:L²(ℝ)→L²(ℝ) by (D af)(x)=a(−1/2)f(x/a) almost everywhere. Which hold?
  6. GATE 2023 MA Q23 (1 mark, Multiple choice) – In real C[0,1] with supremum norm let X=f:f(0)=f(1)=0, S X=f∈X:‖f‖∞=1 and F(f)=∫₀¹f(t)dt. How many elements are in f∈X:F(f)=‖F‖∩S X?
  7. GATE 2023 MA Q37 (2 marks, Multiple choice) – On real ℓ² with usual norm, S(x₁,x₂,…)=(0,x₁,x₂,…) and T(x₁,x₂,…)=(0,x₂,0,x₄,…). Which holds?
  8. GATE 2023 MA Q38 (2 marks, Multiple choice) – Let c₀₀ be finitely supported real sequences with supremum norm. Define F(x) n=(n+1/n)x n and G(x) n=x n/(n+1/n). Which holds?
  9. GATE 2024 MA Q47 (2 marks, Multiple choice) – On finitely supported real sequences C₀₀ define f(x)=Σₙ₌₁∞x n/√n. I:f extends continuously linearly to ℓ¹. II:f extends continuously linearly to ℓ².…
  10. GATE 2024 MA Q49 (2 marks, Multiple select) – X=ℝ² with norm x + y . On S=(x,0), f(x,0)=2x. A Hahn–Banach extension F agrees with f and preserves its norm. Which statements hold?
  11. GATE 2025 MA Q17 (1 mark, Multiple choice) – X=f∈C[0,1]:f(0)=f(1)=0 with sup norm; Y=C[0,1] with L² norm. On their closed unit balls U X,U Y, define Tf=Sf=∫₀¹f(t)dt. S1: sup over U X of Tf is…
  12. GATE 2025 MA Q50 (2 marks, Multiple select) – For 0<α<1, Cα[0,1] is the Hölder Banach space with norm f(0) +sup (s≠t) f(t)−f(s) / t−s α. T:Cα→C[0,1] is inclusion into sup norm. Which statements…
  13. GATE 2026 MA Q32 (1 mark, Numerical answer) – On ℝ³ with ℓ¹ norm, T has matrix pmatrix1&1&3\\2&2&-2\\1&3&-3pmatrix. Find its operator norm (integer).
  14. GATE 2026 MA Q42 (2 marks, Multiple choice) – On ℓ∞ with supremum norm, T(x 1,x 2,)=(x 1,x 2/2,x 3/3,). Which statement holds?
  15. GATE 2026 MA Q53 (2 marks, Multiple select) – For a normed linear space X and its continuous dual X′, which statements hold?