a digital clock shows the time from 00:00 to 23:59 as a string of four digits
1) how many contain for different strings 4 values e.g. 02:43
i got is as 290 don't think its right
since there are
01,02,03,04,05,06,07,08,09,12 = 10
then there are...
yeah its the same as in the other thread but i managed to work out the resolution bit of it and it would not let me edit the post which looked rather cluttered
Homework Statement
Prove by natural deduction
((X \Rightarrow ¬Y)\vee(¬X\RightarrowY))\Rightarrow(¬(X\wedgeY)\wedge¬(¬X\wedge¬Y))
Homework Equations
The Attempt at a Solution
i understand basic natural deduction and how to prove via it but this one has me stumped as there is no...
Homework Statement
Prove by both natural deduction and by resolution
((X \Rightarrow ¬Y)\vee(¬X\RightarrowY))\Rightarrow(¬(X\wedgeY)\wedge¬(¬X\wedge¬Y))Homework Equations
The Attempt at a Solution
as far as natural deduction on this goes i have no idea since there is no ' I- ' looking symbol so...