Assignment Content

Symbolically execute one of the following code listings $($i$.$e$.,$ create a symbolic execution tree$)$ to determine if it ever returns the wrong result. The code listings are both intended to return the minimum of three inputs or$,$ when invalid inputs are provided, an error code $($e$.$g$.,$ null or None$).$

Java Listing

static Integer minimum$($Integer a$,$ Integer b$,$ Integer c$)\{$

if$($a $==$ null $||$ b $==$ null $||$ c $==$ null$)$

return null;

Integer min $=$ a;

if$($min $>=$ c$)\{$

min $=$ c;

if$($min $>=$ b$)\{$

min $=$ b;

$\}$

$\}$

return min;

$\}$

Python Listing

def minimum$($a$,$ b$,$ c$)$:

if not $($isinstance$($a$,$ int$)$ and isinstance$($b$,$ int$)$ and isinstance$($c$,$ int$))$:

return None

min $=$ a

if min $>=$ c:

min $=$ c

if min $>=$ b:

min $=$ b;

return min;

Discuss the symbolic values and path conditional in each of the leaf nodes of the symbolic execution tree to justify that the code is correct or contains an error. If the code contains an error, provide a concrete set of values that illustrates the error.