1. A method of operating a classical computer to calculate a QB net data-set based on a CB net data-set, with the purpose of inducing a quantum computer to calculate a desired probability by operating said quantum computer in accordance with said QB net data-set, said method comprising the steps of: storing said CB net data-set in said classical computer, wherein said CB net data-set comprises: (a) c-graph information comprising a c-node label for each c-node of a plurality of N c-nodes, and also comprising a plurality of directed c-lines, wherein a directed c-line comprises an ordered pair of said c-node labels, wherein one member of the label pair labels the source c-node and the other member labels the destination c-node of the directed c-line, (b) c-state information comprising, for each j∈{1, 2,. .. N}, a finite set S j containing labels for the states that the j'th c-node {circumflex over (x)} j assume, and (c) c-probability information comprising, for each j∈{1, 2,. .. N}, a representation of a non-negative real number P j [ x j ❘ x k 1 , x k 2 , … ⁢ , x k  Γ j  ] for each vector ( x j , ( x. ) Γ j ) = ( x j , x k 1 , x k 2 , … ⁢ , x k  Γ j  ) such that x j ∈S j , x k 1 ∈S k 1 , x k 2 ∈S k 2 ,. .. , and x k  Γ j  ∈ S k  Γ j  , wherein ( x ^ k 1 , x ^ k 2 , … ⁢ , x ^ k  Γ j  ) is the set of all c-nodes for which there is a directed c-line with one element of the set as source c-node and {circumflex over (x)} j as destination c-node, wherein |Γ j |≧0, composing said QB net data-set using said classical computer and said CB net data-set, wherein said QB net data-set comprises: (a′) q-graph information comprising a q-node label for each q-node of a plurality of N′ q-nodes, and also comprising a plurality of directed q-lines, wherein a directed q-line comprises an ordered pair of said q-node labels, wherein one member of the label pair labels the source q-node and the other member labels the destination q-node of the directed q-line, (b′) q-state information comprising, for each j∈{1, 2,. .. N′}, a finite set S′ j containing labels for the states that the j'th q-node ŷ j assumes, and (c′) q-amplitude information comprising, for each j∈{1, 2,. .. N′}, a representation of a complex number A j [ y j ❘ y k 1 , y k 2 , … ⁢ , y k  Γ j ′  ] for each vector ( y j , ( y. ) Γ j ′ ) = ( y j , y k 1 , y k 2 , … ⁢ , y k  Γ j ′  ) such that y j ∈S′ j , y k 1 ∈S′ k 1 , y k 2 ∈S′ k 2 ,. .. , and y k  Γ j ′  ∈ S k  Γ j ′  ′ , wherein ( y ^ k 1 , y ^ k 2 , … ⁢ , y ^ k  Γ j ′  ) is the set of all q-nodes for which there is a directed q-line with one element of the set as source q-node and ŷ j as destination q-node, wherein |Γ′ j |≧0, wherein if P(x.) is defined from said CB net data-set by P ⁡ ( x. ) = ∏ j = 1 N ⁢ ⁢ P j ⁡ [ x j ❘ ( x. ) Γ j ] , and A(y.) is defined from said QB net data-set by A ⁡ ( y. ) = ∏ j = 1 N ′ ⁢ ⁢ A j ⁡ [ y j ❘ ( y. ) Γ j ′ ] , then P(x.) for each (x.)∈S 1 ×S 2 ×.. . S N is constrained to equal a function of A(y.) for all (y.)∈S′ 1 ×S′ 2 ×.. . S′ N′ , said function of A(y.) satisfying the following constraint, if L is the set of all j such that ŷ j is a leaf q-node (i.e., a q-node which is not a source q-node of any directed q-line) of said QB net data-set, and not ⁡ ( L ) = { 1 , 2 , … ⁢ ⁢ N ′ } - L , and A L ⁡ [ ( y. ) L ] = ∑ ( y. ) not ⁡ ( L ) ⁢ A ⁡ ( y. ) , then P(x.) is proportional, with an (x.)-independent proportionality constant, to a sum of some numbers from the set {|A L [(y.)L]| 2 :for all possible values of (y.)L}.