Logical implication with 1 variable

Question

I have the following statements in my knowledge base, but there is a premise with only 1 variable (refer to 3rd line). I'm attempting to build a truth table for this, but the 3rd premise gets me confused as there is only 1 condition to decide the implied condition.

p ^ q ^ r => s;
q ^ r => t;
t => u;   <---- confused line.
p;
s;

For example, according to my knowledge:

p | q | p=>q    
--------------    
0 | 0 | 1    
0 | 1 | 1    
1 | 0 | 0    
1 | 1 | 1

But how do I go about constructing the truth table for 3rd statement here. There's only 1 variable to decide 'u'.

Thank you :)

Answer 1

The truth table would involve t and t=>u; from there you would try to decide u:

t | t=>u | u    
--------------    
0 | 0    | not possible
0 | 1    | 0 or 1
1 | 0    | 0
1 | 1    | 1

If you want t=>u to be 1, then if t is 1, u has to be 1; and if t is 0, then u can be either 0 or 1.