diff --git a/docs/1b/ece124.md b/docs/1b/ece124.md
index 89b9691..bc59fe7 100644
--- a/docs/1b/ece124.md
+++ b/docs/1b/ece124.md
@@ -139,6 +139,14 @@ $$M_j=x_1+x_2+\dots +x_n$$
     &=x_1+x_2+x_3
     \end{align*}
 
+A **canonical sum of products (SOP)** is a function expressed as a sum of minterms.
+
+$$f(x_1,x_2,\dots)=\sum m(a,b, \dots)$$
+
+A **canonical product of sums (POS)** is a function expressed as a product of maxterms.
+
+$$f(x_1,x_2,\dots)=\prod M(a,b,\dots)$$
+
 ## VHDL
 
 VHDL is a hardware schematic language.