In a look $$-$$ ahead carry generator, the carry generate function $${G_i}$$ and the carry propagate function $${P_i}$$ for inputs, $${A_i}$$ and $${B_i}$$ are given by: $${P_i} = {A_i} \oplus {B_i}$$ and $${G_i} = {A_i}{B_i}.$$

The expressions for the sum bit $${S_i}$$ and the carry bit $${C_{i + 1}}$$ of the look ahead carry adder are given by $${S_i} = {P_i} \oplus {C_i}$$ and $${C_{i + 1}} = {G_i} + {P_i}{C_i},$$ where $${C_0}$$ is the input carry. Consider a two $$-$$ level logic implementation of the look $$-$$ ahead carry generator. Assume that all $${P_i}$$ and $${G_i}$$ are available for the carry generator circuit and that the $$AND$$ and $$OR$$ gates can have any number of inputs. The number of $$AND$$ gates and $$OR$$ gates needed to implement the look $$-$$ ahead carry generator for a $$4$$-bit adder with $${S_3},\,\,{S_2},\,\,{S_1},\,\,{S_0}$$ and $${C_4}$$ as its outputs are respectively

Consider a hash function that distributes keys uniformly. The hash table size is 20. After hashing of how many keys will the probability that any new key hashed collides with an existing one exceed 0.5.

Consider a hash table of size seven, with starting index zero, and a hash function (3x + 4)mod7. Assuming the hash table is initially empty, which of the following is the contents of the table when the sequence 1, 3, 8, 10 is inserted into the table using closed hashing? Note that ‘_’ denotes an empty location in the table.

Consider the following two statements:
i. A hash function (these are often used for computing digital signatures) is an injective function.
ii. encryption technique such as DES performs a permutation on the elements of its input alphabet.
Which one of the following options is valid for the above two statements?