Промежуточные таблицы истинности:
X1≡Y1:

¬(X1≡Y1):

X2≡Y2:

(¬(X1≡Y1))≡(X2≡Y2):

Общая таблица истинности:

Логическая схема:

---

Совершенная дизъюнктивная нормальная форма (СДНФ):

По таблице истинности:
F_сднф = ¬X1∧¬Y1∧¬X2∧Y2 ∨ ¬X1∧¬Y1∧X2∧¬Y2 ∨ ¬X1∧Y1∧¬X2∧¬Y2 ∨ ¬X1∧Y1∧X2∧Y2 ∨ X1∧¬Y1∧¬X2∧¬Y2 ∨ X1∧¬Y1∧X2∧Y2 ∨ X1∧Y1∧¬X2∧Y2 ∨ X1∧Y1∧X2∧¬Y2
Логическая cхема:

---

Совершенная конъюнктивная нормальная форма (СКНФ):

По таблице истинности:
F_скнф = (X1∨Y1∨X2∨Y2) ∧ (X1∨Y1∨¬X2∨¬Y2) ∧ (X1∨¬Y1∨X2∨¬Y2) ∧ (X1∨¬Y1∨¬X2∨Y2) ∧ (¬X1∨Y1∨X2∨¬Y2) ∧ (¬X1∨Y1∨¬X2∨Y2) ∧ (¬X1∨¬Y1∨X2∨Y2) ∧ (¬X1∨¬Y1∨¬X2∨¬Y2)
Логическая cхема:

---

Построение полинома Жегалкина:

По таблице истинности функции
Построим полином Жегалкина:
F_ж = C₀₀₀₀ ⊕ C₁₀₀₀∧X1 ⊕ C₀₁₀₀∧Y1 ⊕ C₀₀₁₀∧X2 ⊕ C₀₀₀₁∧Y2 ⊕ C₁₁₀₀∧X1∧Y1 ⊕ C₁₀₁₀∧X1∧X2 ⊕ C₁₀₀₁∧X1∧Y2 ⊕ C₀₁₁₀∧Y1∧X2 ⊕ C₀₁₀₁∧Y1∧Y2 ⊕ C₀₀₁₁∧X2∧Y2 ⊕ C₁₁₁₀∧X1∧Y1∧X2 ⊕ C₁₁₀₁∧X1∧Y1∧Y2 ⊕ C₁₀₁₁∧X1∧X2∧Y2 ⊕ C₀₁₁₁∧Y1∧X2∧Y2 ⊕ C₁₁₁₁∧X1∧Y1∧X2∧Y2

Так как F_ж(0000) = 0, то С₀₀₀₀ = 0.

Далее подставляем все остальные наборы в порядке возрастания числа единиц, подставляя вновь полученные значения в следующие формулы:
F_ж(1000) = С₀₀₀₀ ⊕ С₁₀₀₀ = 1 => С₁₀₀₀ = 0 ⊕ 1 = 1
F_ж(0100) = С₀₀₀₀ ⊕ С₀₁₀₀ = 1 => С₀₁₀₀ = 0 ⊕ 1 = 1
F_ж(0010) = С₀₀₀₀ ⊕ С₀₀₁₀ = 1 => С₀₀₁₀ = 0 ⊕ 1 = 1
F_ж(0001) = С₀₀₀₀ ⊕ С₀₀₀₁ = 1 => С₀₀₀₁ = 0 ⊕ 1 = 1
F_ж(1100) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₁₀₀ ⊕ С₁₁₀₀ = 0 => С₁₁₀₀ = 0 ⊕ 1 ⊕ 1 ⊕ 0 = 0
F_ж(1010) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₀₁₀ ⊕ С₁₀₁₀ = 0 => С₁₀₁₀ = 0 ⊕ 1 ⊕ 1 ⊕ 0 = 0
F_ж(1001) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₀₀₁ ⊕ С₁₀₀₁ = 0 => С₁₀₀₁ = 0 ⊕ 1 ⊕ 1 ⊕ 0 = 0
F_ж(0110) = С₀₀₀₀ ⊕ С₀₁₀₀ ⊕ С₀₀₁₀ ⊕ С₀₁₁₀ = 0 => С₀₁₁₀ = 0 ⊕ 1 ⊕ 1 ⊕ 0 = 0
F_ж(0101) = С₀₀₀₀ ⊕ С₀₁₀₀ ⊕ С₀₀₀₁ ⊕ С₀₁₀₁ = 0 => С₀₁₀₁ = 0 ⊕ 1 ⊕ 1 ⊕ 0 = 0
F_ж(0011) = С₀₀₀₀ ⊕ С₀₀₁₀ ⊕ С₀₀₀₁ ⊕ С₀₀₁₁ = 0 => С₀₀₁₁ = 0 ⊕ 1 ⊕ 1 ⊕ 0 = 0
F_ж(1110) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₁₀₀ ⊕ С₀₀₁₀ ⊕ С₁₁₀₀ ⊕ С₁₀₁₀ ⊕ С₀₁₁₀ ⊕ С₁₁₁₀ = 1 => С₁₁₁₀ = 0 ⊕ 1 ⊕ 1 ⊕ 1 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 1 = 0
F_ж(1101) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₁₀₀ ⊕ С₀₀₀₁ ⊕ С₁₁₀₀ ⊕ С₁₀₀₁ ⊕ С₀₁₀₁ ⊕ С₁₁₀₁ = 1 => С₁₁₀₁ = 0 ⊕ 1 ⊕ 1 ⊕ 1 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 1 = 0
F_ж(1011) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₀₁₀ ⊕ С₀₀₀₁ ⊕ С₁₀₁₀ ⊕ С₁₀₀₁ ⊕ С₀₀₁₁ ⊕ С₁₀₁₁ = 1 => С₁₀₁₁ = 0 ⊕ 1 ⊕ 1 ⊕ 1 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 1 = 0
F_ж(0111) = С₀₀₀₀ ⊕ С₀₁₀₀ ⊕ С₀₀₁₀ ⊕ С₀₀₀₁ ⊕ С₀₁₁₀ ⊕ С₀₁₀₁ ⊕ С₀₀₁₁ ⊕ С₀₁₁₁ = 1 => С₀₁₁₁ = 0 ⊕ 1 ⊕ 1 ⊕ 1 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 1 = 0
F_ж(1111) = С₀₀₀₀ ⊕ С₁₀₀₀ ⊕ С₀₁₀₀ ⊕ С₀₀₁₀ ⊕ С₀₀₀₁ ⊕ С₁₁₀₀ ⊕ С₁₀₁₀ ⊕ С₁₀₀₁ ⊕ С₀₁₁₀ ⊕ С₀₁₀₁ ⊕ С₀₀₁₁ ⊕ С₁₁₁₀ ⊕ С₁₁₀₁ ⊕ С₁₀₁₁ ⊕ С₀₁₁₁ ⊕ С₁₁₁₁ = 0 => С₁₁₁₁ = 0 ⊕ 1 ⊕ 1 ⊕ 1 ⊕ 1 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 ⊕ 0 = 0

Таким образом, полином Жегалкина будет равен:
F_ж = X1 ⊕ Y1 ⊕ X2 ⊕ Y2
Логическая схема, соответствующая полиному Жегалкина: