For a given category KAC2, the present paper deals with an existence problem of the category DT C2(k) which is equivalent to KAC2, where DT C2(k) is the category whose objects are simple closed k-curves with even number l of elements in Z n , l = 6 and morphisms are (digitally) k-continuous maps, and KAC2 is the category whose objects are simple closed A-curves and morphisms are A-maps. To address this issue, the paper starts with the category, denoted by KAC1, whose objects are connected nD Khalimsky topological subspaces with Khalimsky adjacency and morphisms are A-maps in [Han S. E., Sostak A. A compression of digital images derived from a Khalimsky topological structure // Comput. and Appl. Math.-2013.-32.-P. 521-536]. Based on this approach, in KAC1 the paper proposes the notions of an A-homotopy and an A-homotopy equivalence, and classifies spaces in KAC1 or KAC2 in terms of an A-homotopy equivalence. Finally, the paper proves that for a given category KAC2 there is DT C2(k) which is equivalent to KAC2. Для заданої категорiї KAC2 вивчено проблему iснування категорiї DT C2(k), що еквiвалентна KAC2, де DT C2(k)категорiя, об'єктами якої є простi замкненi k-кривi з парним числом l, l = 6, елементiв в Z n , а морфiзмами-(цифрово) k-неперервнi вiдображення, тодi як KAC2-категорiя, об'єктами якої є простi замкненi A-кривi, а морфiзми є A-вiдображеннями. Наш виклад ми починаємо з категорiї, що позначена KAC1, об'єктами якої є nD зв'язнi топологiчнi пiдпростори Халiмського з сумiжнiстю Халiмського, а морфiзми є A-вiдображеннями, що визначенi в [Han S. E., Sostak A. A compression of digital images derived from a Khalimsky topological structure // Comput. and Appl. Math.-2013.-32.-P. 521-536]. На основi запропонованого пiдходу в категорiї KAC1 введено поняття A-гомотопiї та A-гомотопiчної еквiвалентностi, а простори з KAC1 або KAC2 класифiковано в термiнах A-гомотопiчної еквiвалентностi. Насамкiнець доведено, що для заданої категорiї KAC2 iснує DT C2(k), еквiвалентнa KAC2. 1. Introduction. Let Z, N and Z n represent the sets of integers, natural numbers and points in the Euclidean nD space with integer coordinates, respectively. To recognize a set X ⊂ Z n with graph theoretical structures, A. Rosenfeld introduced digital topology [19]. Furthermore, many researchers have developed several tools such as a Marcuse Wyse topological structure [20], a graph theoretical method [4-7, 16, 19], a Khalimsky topological structure [3, 10, 11, 14, 15, 18], a locally finite topological approach [17] and so forth. Nowadays, digital topology plays an important role in some areas of computer science and applied topology such as image processing, computer graphics, image analysis, mathematical morphology and so forth. It has been used to study topological properties and features, e.g., connectedness and boundaries of two, three or nD digital images. Since the paper will frequently refer a Khalimsky topological structure, hereafter, for convenience we will use the terminology K-instead of "Khalimsky" if there is no danger of ambiguity. S...