Fix typos introduced during formatting changes

Fixed the following typos:
- linear_algebra.md: removed extra '.*.' after 'square' and 'symmetric'
- linear_algebra.md: removed extra '.l.' after 'diagonal'
- sir_model.md: removed extra 'd)' after 'infected)'
- von_neumann_model.md: removed extra '.).' after 'consumed)'
- von_neumann_model.md: removed extra '****' after 'outputs'
- von_neumann_model.md: removed extra 'es' from 'activitieses' → 'activities'

Author: mmcky

lectures/linear_algebra.md

@@ -471,15 +471,15 @@ For obvious reasons, the matrix $A$ is also called a vector if either $n = 1$ or
 
 In the former case, $A$ is called a **row vector**, while in the latter it is called a **column vector**.
 
-If $n = k$, then $A$ is called **square**.*.
+If $n = k$, then $A$ is called **square**.
 
 The matrix formed by replacing $a_{ij}$ by $a_{ji}$ for every $i$ and $j$ is called the **transpose** of $A$ and denoted $A'$ or $A^{\top}$.
 
-If $A = A'$, then $A$ is called **symmetric**.*.
+If $A = A'$, then $A$ is called **symmetric**.
 
 For a square matrix $A$, the $i$ elements of the form $a_{ii}$ for $i=1,\ldots,n$ are called the **principal diagonal**.
 
-$A$ is called **diagonal** if the only nonzero entries are on the principal diagonal.l.
+$A$ is called **diagonal** if the only nonzero entries are on the principal diagonal.
 
 If, in addition to being diagonal, each element along the principal diagonal is equal to 1, then $A$ is called the **identity matrix** and denoted by $I$.
 

lectures/sir_model.md

@@ -109,7 +109,7 @@ dynamics are
 In these equations,
 
 * $\beta(t)$ is called the **transmission rate** (the rate at which individuals bump into others and expose them to the virus).
-* $\sigma$ is called the **infection rate** (the rate at which those who are exposed become infected)d)
+* $\sigma$ is called the **infection rate** (the rate at which those who are exposed become infected)
 * $\gamma$ is called the **recovery rate** (the rate at which infected people recover or die).
 * the dot symbol $\dot y$ represents the time derivative $dy/dt$.
 

lectures/von_neumann_model.md

@@ -365,7 +365,7 @@ A pair $(A,B)$ of $m\times n$ non-negative matrices defines
 an economy.
 
 - $m$ is the number of **activities** (or sectors)
-- $n$ is the number of **goods** (produced and/or consumed).).
+- $n$ is the number of **goods** (produced and/or consumed)
 - $A$ is called the **input matrix**; $a_{i,j}$ denotes the
   amount of good $j$ consumed by activity $i$
 - $B$ is called the **output matrix**; $b_{i,j}$ represents
@@ -395,7 +395,7 @@ Therefore,
 
 - vector $x^\top A$ gives the total amount of **goods used in
   production**
-- vector $x^\top B$ gives **total outputs****
+- vector $x^\top B$ gives **total outputs**
 
 An economy $(A,B)$ is said to be **productive**, if there exists a
 non-negative intensity vector $x \geq 0$ such
@@ -407,7 +407,7 @@ the $n$ goods.
 The $p$ vector implies **cost** and **revenue** vectors
 
 - the vector $Ap$ tells **costs** of the vector of activities
-- the vector $Bp$ tells **revenues** from the vector of activitieses
+- the vector $Bp$ tells **revenues** from the vector of activities
 
 Satisfaction of a property of an input-output pair $(A,B)$ called **irreducibility**
 (or indecomposability) determines whether an economy can be decomposed