Hindawi Publishing Corporation Abstract and Applied Analysis Volume 2013, Article ID 750524, 7 pages http://dx.doi.org/10.1155/2013/750524 Research Article Unified Treatment of the Krätzel Transformation for Generalized Functions S. K. Q. Al-Omari1 and A. KJlJçman2 1 2 Department of Applied Sciences, Faculty of Engineering Technology, Al-Balqa Applied University, Amman 11134, Jordan Department of Mathematics and Institute of Mathematical Research, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia Correspondence should be addressed to A. Kılıçman; akilicman@putra.upm.edu.my Received 26 March 2013; Accepted 18 April 2013 Academic Editor: Mustafa Bayram Copyright © 2013 S. K. Q. Al-Omari and A. Kılıçman. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We discuss a generalization of the Krätzel transforms on certain spaces of ultradistributions. We have proved that the Krätzel transform of an ultradifferentiable function is an ultradifferentiable function and satisfies its Parseval’s inequality. We also provide a complete reading of the transform constructing two desired spaces of Boehmians. Some other properties of convergence and continuity conditions and its inverse are also discussed in some detail. 1. Introduction Krätzel, in [1, 2], introduced a generalization of the Meijer transform by the integral: (𝐾V𝑝 𝑓) (𝑥) = ∫ ZV𝑝 (𝑥𝑦) 𝑓 (𝑦) 𝑑𝑦, R+ 𝑥 > 0, (1) where ZV𝑝 (𝑥𝑦) = ∫ 𝑡V−1 𝑒−𝑡 𝑝 −𝑥𝑦/𝑡 R+ 𝑑𝑡, (2) 𝑝 > 0(∈ N), V ∈ C. Then this generalization is known as Krätzel transform. Let 𝑥 be in R+ . Denote by S+ , or S(R+ ), the space of all complex-valued smooth functions 𝜙(𝑡) on R+ such that sup D𝑘 𝜙 (𝑥) < ∞, 𝑥∈K (3) 𝑥 ∈ R+ , where K runs through compact subsets of R+ ; see [3]. The strong dual S+ of S+ consists of distributions of compact supports. Later, the authors in [4] have studied the 𝐾V𝑝 transformation in a space of distributions of compact support inspired by known kernel method. They, also, have obtained its properties of analyticity and boundedness and have established its inversion theorem. In the sense of classical theory, the Meijer transformation and the Laplace transformation in [5] are presented as special forms of the cited transform for 𝑝 = 1 and 𝑝 = 1, V = ±1/2, respectively. It is worth mentioning in this note that a suitable motivation of the cited transform has thoroughly been discussed in [6] by the aid of a Fréchet space of constituted functions of infinitely differentiable functions over (0, ∞). This paper is a continuation of the work obtained in [4]. We are concerned with a general study of the transform in the space of ultradistributions and further discuss its extension to Boehmian spaces in some detail. We are employing the adjoint method and method of kernels for our purpose to extend the classical integral transform to generalized functions and hence ultradistributions. 2. Ultradistributions The theory of ultradistributions is one of generalizations of the theory of Schwartz distributions; see [3, 7]. Since then, in the recent past and even earlier, it was extensively studied by many authors such as Roumieu [8, 9], Komatsu [10], Beurling [11], Carmichael et al. [12], Pathak [13, 14], and Al-Omari [15, 16]. 2 Abstract and Applied Analysis By an ultradifferentiable function we mean an infinitely smooth function whose derivatives satisfy certain growth conditions as the order of the derivatives increases. Unlike sequences presented in [15, 16], 𝑎𝑖 , 𝑖 = 0, 1, . . ., wherever it appears, denotes a sequence of positive real numbers. Such omission of constraints may ease the analysis. Let 𝛼 be a real number but fixed and L𝑟 be the space of Lebesgue integrable functions on R+ . Denote by S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (resp., S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)), 1 ≤ 𝑟 ≤ ∞, the subsets of S+ of all complex valued infinitely smooth functions on R+ such that, for some constant 𝑚1 (> 0), sup D𝑘 𝜑 (𝑥)L𝑟 ≤ 𝑚1 𝑎𝛼 𝑎𝛼 𝛼,𝑥∈K A sequence (𝜑𝑛 ) → S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)) if 𝜑 ∈ 𝑎 > 0. lim sup D𝑘 (𝜑𝑛 (𝑥) − 𝜑 (𝑥))L𝑟 = 0, (5) (6) −𝑥𝑦/𝑡 R+ =∬ 𝑑𝑡𝜙 (𝑦) 𝑑𝑦 −𝑦 V−1 −𝑡𝑝 −𝑥𝑦/𝑡 𝑑𝑡𝜙 (𝑦) 𝑑𝑦 𝑡 𝑒 R+ 𝑡 (V−1)−1 −𝑡𝑝 −𝑥𝑦/𝑡 = ∫ −𝑦 ∫ 𝑡 R+ R+ 𝑒 (8) 𝑑𝑡𝜙 (𝑦) 𝑑𝑦 = ∫ −𝑦ZV−1 𝑝 (𝑥𝑦) 𝜙 (𝑦) 𝑑𝑦. Hence the principle of mathematical induction on the 𝑘th derivative gives 𝑘 D𝑘𝑥 (𝐾V𝑝 𝜙) (𝑥) = (−1)𝑘 ∫ ZV−𝑘 𝑝 (𝑥𝑦) 𝑦 𝜙 (𝑦) 𝑑𝑦. R+ (9) From [4], we deduce that 𝑘 𝑝 D𝑥 (𝐾V 𝜙) (𝑥) (10) (2V−𝑝)/(2𝑝+2) −(𝑥𝑦)𝑝 /(𝑝+1) 𝑘 𝑦 𝜙 (𝑦) 𝑑𝑦 ≤ 𝛼1 ∫ (𝑦) 𝑒 R+ ∈ for some constant 𝛼1 . The assumption that 𝜙 S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) implies that the products under the integral 𝑝 sign, Ψ = 𝑦𝑘 𝜙(𝑦) and (𝑥𝑦)(2V−𝑝)/(2𝑝+2) 𝑒−(𝑥𝑦) /(𝑝+1) Ψ, are also in S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Moreover, 𝜙 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) ensures that the integral: (2V−𝑝)/(2𝑝+2) −(𝑥𝑦)𝑝 /(𝑝+1) 𝑘 𝑒 ϝ (𝑥) = 𝛼1 ∫ (𝑥𝑦) 𝑦 𝜙 (𝑦) 𝑑𝑦 (11) R+ belongs to S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Hence and there is a constant 𝑚1 > 0 independent of 𝑛 such that lim sup D𝑘 (𝜑𝑛 (𝑥) − 𝜑 (𝑥))L𝑟 ≤ 𝑚1 𝑎𝛼 𝑎𝛼 𝑛→∞ 𝛼,𝑥∈K 𝑝 R+ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (resp., 𝑛→∞ 𝛼,𝑥∈K D𝑥 (𝐾V𝑝 𝜙) (𝑥) = ∬ D𝑥 𝑡V−1 𝑒−𝑡 (4) for all 𝑎 > 0 (for some 𝑎 > 0), where K is a compact set traverses R+ . The elements of the dual spaces, S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)), are the Beurlingtype (Roumieu-type) ultradistributions. It may be noted that S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) ⊂ S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎) ⊂ S+ . Thus, every distribution of compact support is an ultradistribution of Roumieu type and further, and an ultradistribution of Roumieu type is of Beurling-type. Natural topologies on S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (resp., S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)) can be generated by the collection of seminorms: 𝑘 D 𝜑 (𝑥) 𝑟 L , 𝜑𝑟,𝑎 = sup 𝑎𝛼 𝑎𝛼 𝛼,𝑥∈K Proof. Let 𝜙 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝑥 be fixed, and then 𝐾V𝑝 𝜙 certainly exists. By differentiation with respect to 𝑥 we get 𝑘 D𝑥 ϝ (𝑥) 𝑟 ≤ 𝑚1 𝑎𝛼 𝑎𝛼 L (7) for all 𝑎 > 0. S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)) is dense in S+ , convergence in S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)) implies convergence in S+ , and consequently a restriction of any 𝑓 ∈ S+ to S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)) is in S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) (S+ (L𝑟 , 𝛼, {𝑎𝑖 }, 𝑎)). 3. The Krätzel Transform of Tempered Ultradistributions (12) for some constant 𝑚1 . Therefore, from the above inequality we get 𝑘 𝑝 D𝑥 (𝐾V 𝜙) (𝑥) 𝑟 ≤ D𝑘𝑥 ϝ (𝑥) 𝑟 ≤ 𝑚1 𝑎𝛼 𝑎𝛼 , L L (13) for certain positive constant 𝑚1 . This proves the lemma. From Lemma 1 we deduce that the Krätzel transform is bounded and closed from S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) into itself. Next, we establish the Parseval’s relation for the Krätzel transform. In this section of this paper we define the Krätzel transform of tempered ultradistributions by using both of kernel and adjoint methods. We restrict our investigation to the case of Beurling type since the other investigation for the Roumieutype tempered ultradistributions is almost similar. Theorem 2. Let 𝑓 and 𝑔 be absolutely integrable functions over R+ and then Lemma 1. Let 𝜙 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and then 𝐾V𝑝 𝜙 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). where 𝐾V𝑝 𝑓 and 𝐾V𝑝 𝑔 are the Krätzel transforms of 𝑓 and 𝑔, respectively. ∫ 𝑓 (𝑥) (𝐾V𝑝 𝑔) (𝑥) 𝑑𝑥 = ∫ (𝐾V𝑝 𝑓) (𝑥) 𝑔 (𝑥) 𝑑𝑥, R+ R+ (14) Abstract and Applied Analysis 3 Proof. It is clear that 𝐾V𝑝 𝑓 and 𝐾V𝑝 𝑔 are continuous and bounded on R+ . Moreover, the Fubini’s theorem allows us to interchange the order of integration: ∫ 𝑓 (𝑥) (𝐾V𝑝 𝑔) (𝑥) 𝑑𝑥 R+ (15) = ∫ (∫ R+ R+ 𝑓 (𝑥) ZV𝑝 (𝑥𝑦) 𝑑𝑥) 𝑔 (𝑦) 𝑑𝑦. Equation (15) follows since the Krätzel kernel ZV𝑝 (𝑥𝑦) applies for the functions 𝑓 and 𝑔, when the order of integration is interchanged. This completes the proof of the theorem. Now, in consideration of Theorem 2, the adjoint method of extending the Krätzel transform can be read as ⟨𝐾V𝑝 𝑓, 𝜙⟩ = ⟨𝑓, 𝐾V𝑝 𝜙⟩ , (16) Theorem 3. Given that 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) then 𝐾V𝑝 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Proof. Consider a zero convergent sequence (𝜙𝑛 ) in S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) then certainly (𝐾V𝑝 𝜙𝑛 ) is a zero-convergent sequence in the same space. It follows from (16) that = ⟨𝑓, 𝐾V𝑝 𝜙𝑛 ⟩ → 0 as 𝑛 → ∞. and then 𝐾V𝑝 𝑓 is Proof. See [4, Proposition 2.3]. It is interesting to know that the Krätzel transform can be defined in an alternative way, namely, by the kernel method. Let 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎), and then (𝐾V𝑝 𝑓) (𝑥) = ⟨𝑓 (𝑦) , ZV𝑝 (𝑥𝑦)⟩ . Theorem 5. Let 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) then 𝐾V𝑝 𝑓 is infinitely differentiable and for every 𝑘 ∈ N and 𝑥 ∈ R+ . Proof. See [4, Proposition 2.2]. Elements of Δ are called delta sequences. Consider If (𝑥𝑛 , 𝑠𝑛 ), (𝑦𝑛 , 𝑡𝑛 ) ∈ g, 𝑥𝑛 ⊙ 𝑡𝑚 = 𝑦𝑚 ⊙ 𝑠𝑛 , for all 𝑚, 𝑛 ∈ N, then we say (𝑥𝑛 , 𝑠𝑛 ) ∼ (𝑦𝑛 , 𝑡𝑛 ). The relation ∼ is an equivalence relation in g. The space of equivalence classes in g is denoted by 𝛽. Elements of 𝛽 are called Boehmians. Between A and 𝛽 there is a canonical embedding expressed as 𝑥 → 𝑥 ⊙ 𝑠𝑛 . 𝑠𝑛 (21) 𝑥𝑛 𝑥 ⊙𝑡 ⊙𝑡= 𝑛 . 𝑠𝑛 𝑠𝑛 (22) In 𝛽, there are two types of convergence: (𝛿 convergence) a sequence (ℎ𝑛 ) in 𝛽 is said to be 𝛿 𝛿 convergent to ℎ in 𝛽, denoted by ℎ𝑛 → ℎ, if there exists a delta sequence (𝑠𝑛 ) such that (ℎ𝑛 ⊙𝑠𝑛 ), (ℎ⊙𝑠𝑛 ) ∈ A, for all 𝑘, 𝑛 ∈ N, and (ℎ𝑛 ⊙𝑠𝑘 ) → (ℎ⊙𝑠𝑘 ) as 𝑛 → ∞, in A, for every 𝑘 ∈ N, (Δ convergence) a sequence (ℎ𝑛 ) in 𝛽 is said to be Δ Δ convergent to ℎ in 𝛽, denoted by ℎ𝑛 → ℎ, if there exists a (𝑠𝑛 ) ∈ Δ such that (ℎ𝑛 − ℎ) ⊙ 𝑠𝑛 ∈ A, for all 𝑛 ∈ N, and (ℎ𝑛 − ℎ) ⊙ 𝑠𝑛 → 0 as 𝑛 → ∞ in A. For further discussion see [17–21]. (18) In fact, (18) is a straightforward consequence of Lemma 1. D𝑘𝑥 (𝐾V𝑝 𝑓) (𝑥) = ⟨𝑓 (𝑡) , D𝑘𝑥 ZV𝑝 (𝑥𝑡)⟩ (a) if 𝑥, 𝑦 ∈ A, (𝑠𝑛 ) ∈ Δ, 𝑥 ⊙ 𝑠𝑛 = 𝑦 ⊙ 𝑠𝑛 for all 𝑛, then 𝑥 = 𝑦, (b) if (𝑠𝑛 ), (𝑡𝑛 ) ∈ Δ, then (𝑠𝑛 ∗ 𝑡𝑛 ) ∈ Δ. The operation ⊙ can be extended to 𝛽 × A by From the above theorem we deduce that the Krätzel transform of a tempered ultradistribution is a tempered ultradistribution. Moreover, the boundedness property of 𝐾V𝑝 𝑓, 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) follows from the following theorem. Theorem 4. Let 𝑓 ∈ bounded. (i) a nonempty set 𝐴, (ii) a commutative semigroup (B, ∗), (iii) an aperation ⊙ : A × B → A such that for each 𝑥 ∈ A and 𝑠1 , 𝑠2 ∈ B, 𝑥 ⊙ (𝑠1 ∗ 𝑠2 ) = (𝑥 ⊙ 𝑠1 ) ⊙ 𝑠2 , (iv) a collection Δ ⊂ B𝑁 such that (17) Linearity is obvious. This completes the proof. S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) Boehmians were first constructed as a generalization of regular Mikusinski operators [17]. The minimal structure necessary for the construction of Boehmians consists of the following elements: g = {(𝑥𝑛 , 𝑠𝑛 ) : 𝑥𝑛 ∈ A, (𝑠𝑛 ) ∈ Δ, 𝑥𝑛 ⊙𝑠𝑚 = 𝑥𝑚 ⊙𝑠𝑛 , ∀𝑚, 𝑛 ∈ N} . (20) where 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝜙 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). ⟨𝐾V𝑝 𝑓, 𝜙𝑛 ⟩ 4. Boehmian Spaces (19) 5. The Ultra-Boehmian Space 𝛽𝑠+ Denote by D+ , or D (R+ ), the Schwartz space of C∞ functions of bounded support. Let Δ + be the family of sequences (𝑠𝑛 ) ∈ D (R+ ) such that the following holds: (Δ 1 ) ∫R 𝑠𝑛 (𝑥)𝑑𝑥 = 1, for all 𝑛 ∈ N, + (Δ 2 ) 𝑠𝑛 (𝑥) ≥ 0, for all 𝑛 ∈ N, (Δ 3 ) supp 𝑠𝑛 ⊂ (0, 𝜀𝑛 ), 𝜀𝑛 → 0 as 𝑛 → ∞. It is easy to see that each (𝑠𝑛 ) in Δ + forms a delta sequence. 4 Abstract and Applied Analysis Let 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝜎 ∈ D (R+ ) be related by the expression: (𝑓 ⋅ 𝜎) 𝜐 = 𝑓 (𝜎 ⊛ 𝜐) , (23) (𝜎 ⊛ 𝜐) (𝑥) = ∫ 𝜎 (𝑡) 𝜐 (𝑥𝑡) 𝑑𝑡 (24) where R+ Lemma 8. Let 𝑓𝑛 , 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝜎 ∈ D+ and then 𝑓𝑛 ⋅ 𝜎 → 𝑓 ⋅ 𝜎. (30) Proof. Let 𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and then 𝜎 ⊛ 𝜐 S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Therefore (𝑓𝑛 ⋅ 𝜎 − 𝑓 ⋅ 𝜎) 𝜐 = ((𝑓𝑛 − 𝑓) ⋅ 𝜎) 𝜐 = (𝑓𝑛 − 𝑓) (𝜎 ⊛ 𝜐) . (31) for every 𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Hence 𝑓𝑛 ⋅ 𝜎 → 𝑓 ⋅ 𝜎 as 𝑛 → ∞. Lemma 6. Let 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝜎 ∈ D+ and then 𝑓 ⋅ 𝜎 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Lemma 9. Let 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and (𝑠𝑛 ) ∈ Δ + then Proof. Using the weak topology of S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎), we write (𝑓 ⋅ 𝜎) 𝜐 = 𝑓 (𝜎 ⊛ 𝜐) ≤ 𝐶‖𝜎 ⊛ 𝜐‖𝑟,𝑎 , (25) where 𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Hence, to complete the proof, we are merely required to show that 𝜎⊛𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). First, if 𝜎 ∈ D+ and 𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎), then choosing a compact set K containing the support of 𝜎 yields (𝜎 ⊛ 𝜐) (𝑥 + Δ𝑥) − (𝜎 ⊛ 𝜐) (𝑥) Δ𝑥 in S+ (L𝑟 , 𝛼, (𝑎𝑖 ) , 𝑎) 𝑓 ⋅ 𝑠𝑛 → 𝑓 as 𝑛 → ∞. (26) Proof. Let 𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and supp 𝑠𝑛 ⊂ (0, 𝜀𝑛 ), 𝑛 ∈ N and then (𝑓 ⋅ 𝑠𝑛 ) 𝜐 = 𝑓 (𝑠𝑛 ⊛ 𝜎) . D𝑘𝑥 (𝜎 ⊛ 𝜐) = 𝜎 ⊛ D𝑘𝑥 𝜐. (27) It is sufficient to establish that 𝑠𝑛 ⊛ 𝜐 → 𝜐 as 𝑛 → ∞. By using (27) and Δ 1 imply that 𝑟 ∫ D𝑘𝑥 (𝑠𝑛 ⊛ 𝜐 − 𝜐) (𝑥) 𝑑𝑥 R 𝑟 = ∫ (𝑠𝑛 ⊛ D𝑘𝑥 𝜐 − D𝑘𝑥 𝜐) (𝑥) 𝑑𝑥 R Hence, the mean value theorem implies 𝑟 ∫ D𝑘𝑥 (𝑠𝑛 ⊛ 𝜐 − 𝜐) (𝑥) 𝑑𝑥 R 𝑟 𝜀𝑛 ≤ ∫ ∫ 𝜉𝑠𝑛 (𝑡) D𝑘+1 𝜐 𝑑𝑡 (𝑥𝜉) 𝑑𝑥, 𝑥 R+ 0 𝑟 𝑟 ∫ D𝑘 (𝜎 ⊛ 𝜐) (𝑥) 𝑑𝑥 = ∫ (𝜎 ⊛ D𝑘 𝜐) (𝑥) 𝑑𝑥 R R + ≤ ∫ ∫ 𝜎 (𝑡) 𝑑𝑡D𝑘 𝜐 (𝑥𝑡) 𝑑𝑥 R K 𝑟 + 𝑟 ≤ 𝑀 ∫ D𝑘 𝜐 (𝑥𝑡) 𝑑𝑥. R + (28) Therefore ‖𝜎 ⊛ 𝜐‖𝑟,𝑎 ≤ 𝑑‖𝜐‖𝑟,𝑎 < 𝑑𝑎𝛼 𝑎𝛼 for some constant 𝑑. (29) Thus 𝜎 ⊛ 𝜐 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). This completes the proof of the lemma. Lemma 7. Let 𝑓1 , 𝑓2 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝜎 ∈ D+ and then Proof of the above Lemma is obvious. (34) 𝑟 𝜀𝑛 = ∫ ∫ 𝑠𝑛 (𝑡) (D𝑘𝑥 𝜐 (𝑥𝑡) − D𝑘𝑥 𝜐 (𝑥)) 𝑑𝑡 𝑑𝑥. R+ 0 + Finally (ii) (𝑓1 + 𝑓2 ) ⋅ 𝜎 = 𝑓1 ⋅ 𝜎1 + 𝑓2 ⋅ 𝜎2 . (33) + which is dominated by 𝜎(𝑡)|D𝑥 𝜐(𝑥)|. The dominated convergence theorem and the principle of mathematical induction implies (i) 𝛼𝑓 ⋅ 𝜎 = 𝛼(𝑓 ⋅ 𝜎), 𝛼 ∈ C, (32) + 𝜐 ((𝑥 + Δ𝑥) 𝑡) − 𝜐 (𝑥𝑡) = ∫ 𝜎 (𝑡) 𝑑𝑡 Δ𝑥 R+ + ∈ (35) 𝜉 ∈ (0, 𝑡). Let 𝐴 1 = sup𝑠∈K |D𝑘+1 𝑥 𝜓(𝑠)|, where K is certain compact set. The calculations show that 𝑠𝑛 ⊛ 𝜐 − 𝜐𝑟,𝑎 ≤ 𝐹𝜀𝑛 → 0 as 𝑛 → ∞, (36) where 𝐹 is certain constant. Hence Lemma 9. The Boehmian space 𝛽𝑠+ is therefore constructed. 6. 𝛽Z+ and the Krätzel Transform of Ultra-Boehmians Denote by Z(R+ ), or Z+ , the space of functions which are Krätzel transforms of ultradistributions in S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎), and then convergence on Z+ can be defined in such away that 𝐸𝑛 → 𝐸∗ in Z+ if 𝑓𝑛 → 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) as 𝑛 → ∞, where 𝐸𝑛 = 𝐾V𝑝 𝑓𝑛 and 𝐸∗ = 𝐾V𝑝 𝑓. Let 𝐸 ∈ Z+ and 𝜎 ∈ D+ and then it is proper to define (𝐸 ⊚ 𝜎) (𝑢) = ∫ 𝐸 (𝑢𝑡) 𝜎 (𝑡) 𝑑𝑡 R+ for each 𝑢 ∈ R+ . (37) Abstract and Applied Analysis 5 Lemma 10. Let 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) and 𝜎 ∈ D+ and then 𝐾V𝑝 (𝑓 ⋅ 𝜎) = 𝐾V𝑝 𝑓 ⊚ 𝜎. Lemma 16. K⃗ 𝑝V : 𝛽𝑠+ → 𝛽Z+ is well defined and linear mapping. Proof. Let K be a compact set containing the support of 𝜎, and then from (18) it follows that Proof is a straightforward conclusion of definitions. 𝐾V𝑝 (𝑓 ⋅ 𝜎) (𝑢) = ⟨(𝑓 ⋅ 𝜎) (𝑦) , ZV𝑝 (𝑢𝑦)⟩ Definition 17. Let [𝐸𝑛 /𝑠𝑛 ] ∈ 𝛽Z+ and then the inverse of K⃗ is defined as follows: −1 = ⟨𝑓 (𝑦) , ⟨𝜎 (𝑡) , ZV𝑝 ((𝑢𝑡) 𝑦)⟩⟩ = ∫ R+ ⟨𝑓 (𝑦) , ZV𝑝 𝑝 ((𝑢𝑡) 𝑦)⟩ 𝜎 (𝑡) 𝑑𝑡 = 𝐾V𝑝 𝑓⊚𝜎. (38) Lemma 11. Let 𝐸 ∈ Z+ and 𝜎 ∈ D+ and then 𝐸 ⊚ 𝜎 ∈ Z+ . Proof. 𝐸 ∈ Z+ implies 𝐾V𝑝 𝑓 = 𝐸, for some 𝑓 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎). Hence 𝐸 ⊚ 𝜎 = 𝐾V𝑝 𝑓 ⊚ 𝜎 = 𝐾V𝑝 (𝑓 ⋅ 𝜎) ∈ Z+ . The following are lemmas which can be easily proved by the aid of the corresponding lemmas from the previous −1 𝑝 section. Detailed proof is avoided. First, if 𝐾V is the inverse Krätzel transform of 𝐾V𝑝 , and then Lemma 12. Let 𝐸 ∈ Z+ and 𝜎 ∈ D+ and then 𝑝 −1 𝑝 𝐾V (𝐸 ⊚ 𝜎) = 𝐾V 𝐸 ⋅ 𝜎. for each (𝑠𝑛 ) ∈ Δ + . (39) Proof. Assume K⃗ 𝑝V [𝑓𝑛 /𝑠𝑛 ] = K⃗ 𝑝V [𝑔𝑛 /𝑡𝑛 ], then it follows from (41) and the concept of quotients of two sequences 𝐾V𝑝 𝑓𝑛 ⊚ 𝑡𝑚 = 𝐾V𝑝 𝑔𝑚 ⊚ 𝑠𝑛 . Therefore, Lemma 10 implies 𝐾V𝑝 (𝑓𝑛 ⋅ 𝑡𝑚 ) = 𝐾V𝑝 (𝑔𝑚 ⋅ 𝜙𝑛 ). Employing properties of 𝐾V𝑝 implies 𝑓𝑛 ⋅ 𝑡𝑚 = 𝑔𝑚 ⋅ 𝑠𝑛 . Thus, [𝑓𝑛 /𝑠𝑛 ] = [𝑔𝑛 /𝑡𝑛 ]. Next we establish that K⃗ 𝑝V is onto. Let [𝐾V𝑝 𝑓𝑛 /𝑠𝑛 ] ∈ 𝛽Z+ be arbitrary and then 𝐾V𝑝 𝑓𝑛 ⊚ 𝑠𝑚 = 𝐾V𝑝 𝑓𝑚 ⊚ 𝑠𝑛 for every 𝑚, 𝑛 ∈ N. Hence 𝑓𝑛 , 𝑓𝑚 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) are such that 𝐾V𝑝 (𝑓𝑛 ⋅ 𝑠𝑚 ) = 𝐾V𝑝 (𝑓𝑚 ⋅ 𝑠𝑛 ). Hence the Boehmian [𝑓𝑛 /𝑠𝑛 ] ∈ 𝛽𝑠+ satisfies the equation K⃗ 𝑝V [𝑓𝑛 /𝑠𝑛 ] = [𝐾V𝑝 𝑓𝑛 /𝑠𝑛 ]. This completes the proof of the lemma. Lemma 19. Let [𝐸𝑛 /𝑠𝑛 ] ∈ 𝛽Z+ , 𝐸𝑛 = 𝐾V𝑝 𝑓𝑛 , and 𝜙 ∈ D+ and then −1 (1) (𝐸1 + 𝐸2 ) ⊚ 𝜎1 = 𝐸1 ⊚ 𝜎1 + 𝐸2 ⊚ 𝜎1 , Lemma 14. Let 𝐸𝑛 → 𝐸 and (𝑠𝑛 ) ∈ Δ + and then 𝐸𝑛 ⊚ 𝑠𝑛 → 𝐸. Lemma 15. Let 𝐸𝑛 → 𝐸 and 𝜎 ∈ D+ and then 𝐸𝑛 ⊚𝜎 → 𝐸⊚𝜎. With the previous analysis, the Boehmian space 𝛽Z+ is constructed. The sum of two Boehmians and multiplication by a scalar in 𝛽Z+ is defined in a natural way [𝑓𝑛 /𝜙𝑛 ] + [𝑔𝑛 /𝜓𝑛 ] = [((𝑓𝑛 ⊚ 𝜓𝑛 ) + (𝑔𝑛 ⊚ 𝜙𝑛 ))/(𝜙𝑛 ⊚ 𝜓𝑛 )] and 𝛼[𝑓𝑛 /𝜙𝑛 ] = [𝛼(𝑓𝑛 /𝜙𝑛 )], 𝛼 ∈ C. The operation ⊚ and the differentiation are defined by D𝑘 [ 𝑓𝑛 D𝑘 𝑓𝑛 ]=[ ]. 𝜙𝑛 𝜙𝑛 (40) With the aid of Lemma 10 we define the extended Krätzel transform of a Boehmian [𝑓𝑛 /𝑠𝑛 ] ∈ 𝛽𝑠+ to be a Boehmian in 𝛽z+ expressed by the relation: 𝐾𝑝 𝑓 𝑓 K⃗ 𝑝V [ 𝑛 ] = [ V 𝑛 ] . 𝑠𝑛 𝑠𝑛 (43) 𝑓 𝐸 K⃗ 𝑝V ([ 𝑛 ] ∙ 𝜙) = [ 𝑛 ] ⊚ 𝜙. 𝑠𝑛 𝑠𝑛 (2) (𝑎𝐸) ⊚ 𝜎1 = 𝑎(𝐸 ⊚ 𝜎1 ). 𝑓𝑛 𝑔 𝑓 ⊚ 𝑔𝑛 ]⊚[ 𝑛] = [ 𝑛 ], 𝜙𝑛 𝜓𝑛 𝜙𝑛 ⊚ 𝜓𝑛 −1 𝐸 𝐸 𝑝 K⃗ V ([ 𝑛 ] ⊚ 𝜙) = [ 𝑛 ] ⋅ 𝜙, 𝑠𝑛 𝑠𝑛 Lemma 13. Let 𝐸1 , 𝐸2 ∈ Z+ and then for all 𝜎1 , 𝜎2 ∈ D+ we have [ (42) Lemma 18. K⃗ 𝑝V is an isomorphism from 𝛽𝑠+ into 𝛽Z+ . Hence the lemma follows. −1 −1 𝐸 𝐾V 𝐸𝑛 ] 𝑝 K⃗ V [ 𝑛 ] = [ , 𝑠𝑛 𝑠𝑛 [ ] (41) Proof. It follows from (42) that −1 𝑝 −1 −1 𝐾V (𝐸𝑛 ⊚ 𝜙) ] 𝐸 ⊚𝜙 𝐸 𝑝 𝑝 K⃗ V ([ 𝑛 ] ⊚ 𝜙) = K⃗ V ([ 𝑛 ]) = [ . 𝑠𝑛 𝑠𝑛 𝑠𝑛 [ ] (44) Applying Lemma 12 leads to −1 −1 𝐸−1 𝐾V 𝐸𝑛 ] 𝐸 𝑝 ⋅ 𝜙 = [ 𝑛 ] ⋅ 𝜙. K⃗ V ([ 𝑛 ] ⊚ 𝜙) = [ 𝑠𝑛 𝑠𝑛 𝑠𝑛 [ ] 𝑝 (45) Proof of the second part is similar. This completes the proof of the lemma. −1 𝑝 Theorem 20. K⃗ 𝑝V : 𝛽𝑠+ → 𝛽Z+ and K⃗ V : 𝛽Z+ → 𝛽𝑠+ are continuous with respect to 𝛿 and Δ convergences. −1 𝑝 Proof. First of all, we show that K⃗ 𝑝V : 𝛽𝑠+ → 𝛽Z+ and K⃗ V : 𝛽Z+ → 𝛽𝑠+ are continuous with respect to 𝛿 convergence. 𝛿 Let 𝛽𝑛 → 𝛽 in 𝛽𝑠+ as 𝑛 → ∞ and then we establish that 6 Abstract and Applied Analysis K⃗ 𝑝V 𝛽𝑛 → K⃗ 𝑝V 𝛽 as 𝑛 → ∞. In view of [10], there are 𝑓𝑛,𝑘 and 𝑓𝑘 in S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎) such that 𝛽𝑛 = [ 𝑓𝑛,𝑘 ], 𝑠𝑘 𝛽=[ 𝑓𝑘 ] 𝑠𝑘 (46) such that 𝑓𝑛,𝑘 → 𝑓𝑘 as 𝑛 → ∞ for every 𝑘 ∈ N. The continuity condition of the Krätzel transform implies 𝐸𝑛,𝑘 → 𝐸𝑘 as 𝑛 → ∞, 𝐸𝑛,𝑘 = 𝐾V𝑝 𝑓𝑛,𝑘 , and 𝐸𝑘 = 𝐾V𝑝 𝑓𝑘 in the space Z+ . Thus, [𝐸𝑛,𝑘 /𝑠𝑘 ] → [𝐸𝑘 /𝑠𝑘 ] as 𝑛 → ∞ in 𝛽Z+ . 𝛿 𝑔 ∈ To prove the second part of the lemma, let 𝑔𝑛 → 𝛽Z+ as 𝑛 → ∞. From [10], we have 𝑔𝑛 = [𝐸𝑛,𝑘 /𝑠𝑘 ] and 𝑔 = [𝐸𝑘 /𝑠𝑘 ] for some 𝐸𝑛,𝑘 , 𝐸𝑘 ∈ Z+ where 𝐸𝑛,𝑘 → 𝐸𝑘 as −1 −1 𝑝 𝑝 𝑛 → ∞. Hence 𝐾V 𝐸𝑛,𝑘 → 𝐾V 𝐸𝑘 in 𝛽𝑠+ as 𝑛 → ∞. −1 That is, [𝐸𝑛,𝑘 /𝑠𝑘 ] → [𝐸𝑘−1 /𝑠𝑘 ] as 𝑛 → ∞. Using (42) we −1 −1 𝑝 𝑝 get K⃗ V [𝐸𝑛,𝑘 /𝑠𝑘 ] → K⃗ V [𝐸𝑘 /𝑠𝑘 ] as 𝑛 → ∞. −1 𝑝 Now, we establish continuity of K⃗ 𝑝V and K⃗ V with respect Δ → 𝛽 in 𝛽𝑠+ as 𝑛 → ∞. Then, we to Δ + convergence. Let 𝛽𝑛 find 𝑓𝑛 ∈ S+ (L𝑟 , 𝛼, (𝑎𝑖 ), 𝑎), and (𝑠𝑛 ) ∈ Δ + such that (𝛽𝑛 − 𝛽) ⋅ 𝑠𝑛 = [(𝑓𝑛 ⋅ 𝑠𝑘 )/𝑠𝑘 ] and 𝑓𝑛 → 0 as 𝑛 → ∞. Employing (41) we get 𝐾𝑝 (𝑓 ⋅ 𝑠 ) K⃗ 𝑝V ((𝛽𝑛 − 𝛽) ⋅ 𝑠𝑛 ) = [ V 𝑛 𝑘 ] . 𝑠𝑘 (47) Hence, from (41) and Lemma 19 we have K⃗ 𝑝V ((𝛽𝑛 − 𝛽) ⋅ 𝑠𝑛 ) = [(𝐸𝑛 ⊚ 𝑠𝑘 )/𝑠𝑘 ] = 𝐸𝑘 → 0 as 𝑛 → ∞ in Z+ . Therefore K⃗ 𝑝V ((𝛽𝑛 − 𝛽) ⋅ 𝑠𝑛 ) (48) = (K⃗ 𝑝V 𝛽𝑛 − K⃗ 𝑝V 𝛽) ⊚ 𝑠𝑛 → 0 as 𝑛 → ∞. Δ Δ Hence, K⃗ 𝑝V 𝛽𝑛 → K⃗ 𝑝V 𝛽 as 𝑛 → ∞. Finally, let 𝑔𝑛 → 𝑔 in 𝛽Z+ as 𝑛 → ∞ and then we find 𝐸𝑘 ∈ Z+ such that (𝑔𝑛 − 𝑔) ⊚ 𝑠𝑛 = [(𝐸𝑘 ⊚ 𝑠𝑘 )/𝑠𝑘 ] and 𝐸𝑘 → 0 as 𝑛 → ∞ for some (𝑠𝑛 ) ∈ Δ + and 𝐸𝑘 = 𝐾V𝑝 𝑓𝑛 . −1 −1 𝑝 𝑝 Next, using (42), we obtain K⃗ V ((𝑔𝑛 −𝑔)⊚𝑠𝑛 ) = [𝐾V (𝐸𝑘 ⊚ 𝑠𝑘 )/𝑠𝑘 ]. Lemma 19 implies that −1 𝑝 K⃗ V ((𝑔𝑛 − 𝑔) ⊚ 𝑠𝑛 ) =[ 𝑓𝑛 ⋅ 𝑠𝑘 ] = 𝑓𝑛 → 0 as 𝑛 → ∞ in S+ (L𝑟 , 𝛼, (𝑎𝑖 ) , 𝑎) . 𝑠𝑘 (49) −1 −1 −1 𝑝 𝑝 𝑝 Thus K⃗ V ((𝑔𝑛 −𝑔)⊚𝑠𝑛 ) = (K⃗ V 𝑔𝑛 − K⃗ V 𝑔)⋅𝑠𝑛 → 0 as 𝑛 → ∞. −1 −1 Δ 𝑝 𝑝 Hence, we have K⃗ V 𝑔𝑛 → K⃗ V 𝑔 as 𝑛 → ∞ in 𝛽𝑠+ . This completes the proof of the theorem. Acknowledgment The authors express their sincere thanks to the referees for the careful and detailed reading of the earlier version of paper and the very helpful suggestions that improved the paper substantially. The second author also acknowledges that this project was partially supported by University Putra Malaysia under the ERGS Grant Scheme with Project no. 5527068. References [1] E. Krätzel, “Integral transformations of Bessel-type,” in Generalized Functions and Operational Calculus (Proc. Conf., Varna, 1975), pp. 148–155, Bulgarian Academy of Sciences, Sofia, Bulgaria, 1979. [2] E. Krätzel and H. Menzer, “Verallgemeinerte HankelFunktionen,” Publicationes Mathematicae Debrecen, vol. 18, pp. 139–147, 1971. [3] A. H. Zemanian, Distribution Theory and Transform Analysis, Dover Publications, New York, NY, USA, 2nd edition, 1987. [4] D. I. Cruz-Báez and J. Rodrı́guez Expósito, “New inversion formulas for the Krätzel transformation,” International Journal of Mathematics and Mathematical Sciences, vol. 25, no. 4, pp. 253–263, 2001. [5] A. H. Zemanian, Generalized Integral Transformations, Dover Publications, New York, NY, USA, 2nd edition, 1987. [6] J. A. Barrios and J. J. Betancor, “A Krätzel’s integral transformation of distributions,” Collectanea Mathematica, vol. 42, no. 1, pp. 11–32, 1991. [7] B. Fisher and A. Kiliçman, “A commutative neutrix product of ultradistributions,” Integral Transforms and Special Functions, vol. 4, no. 1-2, pp. 77–82, 1996. [8] C. Roumieu, “Ultra-distributions définies sur 𝑅𝑛 et sur certaines classes de variétés différentiables,” Journal d’Analyse Mathématique, vol. 10, pp. 153–192, 1963. [9] C. Roumieu, “Sur quelques extensions de la notion de distribution,” Annales Scientifiques de l’École Normale Supérieure. Troisième Série, vol. 77, pp. 41–121, 1960. [10] H. Komatsu, “Ultradistributions. I. Structure theorems and a characterization,” Journal of the Faculty of Science. University of Tokyo. Section IA. Mathematics, vol. 20, pp. 25–105, 1973. [11] A. Beurling, Quasi-Analiticity and Generalized Distributions, Lectures 4 and 5, A. M. S. Summer Institute, Stanford, Calif, USA, 1961. [12] R. D. Carmichael, R. S. Pathak, and S. Pilipović, “Cauchy and Poisson integrals of ultradistributions,” Complex Variables. Theory and Application, vol. 14, no. 1–4, pp. 85–108, 1990. [13] R. S. Pathak, Integral Transforms of Generalized Functions and Their Applications, Gordon and Breach Science Publishers, Amsterdam, The Netherlands, 1997. [14] R. S. Pathak, “A distributional generalised Stieltjes transformation,” Proceedings of the Edinburgh Mathematical Society. Series II, vol. 20, no. 1, pp. 15–22, 1976. [15] S. K. Q. Al-Omari, “Certain class of kernels for Roumieu-type convolution transform of ultra-distributions of compact support,” Journal of Concrete and Applicable Mathematics, vol. 7, no. 4, pp. 310–316, 2009. [16] S. K. Q. Al-Omari, “Cauchy and Poison integrals of tempered ultradistributions of Roumieu and Beurling types,” Journal of Concrete and Applicable Mathematics, vol. 7, no. 1, pp. 36–46, 2009. [17] T. K. Boehme, “The support of Mikusiński operators,” Transactions of the American Mathematical Society, vol. 176, pp. 319–334, 1973. Abstract and Applied Analysis [18] S. K. Q. Al-Omari, D. Loonker, P. K. Banerji, and S. L. Kalla, “Fourier sine (cosine) transform for ultradistributions and their extensions to tempered and ultraBoehmian spaces,” Integral Transforms and Special Functions, vol. 19, no. 5-6, pp. 453–462, 2008. [19] P. Mikusiński, “Fourier transform for integrable Boehmians,” The Rocky Mountain Journal of Mathematics, vol. 17, no. 3, pp. 577–582, 1987. [20] P. Mikusiński, “Tempered Boehmians and ultradistributions,” Proceedings of the American Mathematical Society, vol. 123, no. 3, pp. 813–817, 1995. [21] R. Roopkumar, “Mellin transform for Boehmians,” Bulletin of the Institute of Mathematics. Academia Sinica. 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