Building Converters using Logical Gates for 4-bit Inputs

[alexmath]

Homework Statement

I have to build some converters (only for 4 bits) and i didn't understand how. How do i proceed? Which logical gates combined in such a way give me the y3y2y1y0 answer for x3x2x1x0?
For example, build a coverter from EXCES3 to BCD, or from GRAY TO BCD, or C1 complement to C2 using logical gates (AND,OR,XOR,NAND,etc.)

Homework Equations

The Attempt at a Solution

Well, i can make the truth table for x3x2x1x0.
Thank you!

 

[CWatters]

0011 in Binary is 3 in decimal = one digit wide output = 4 bits
1100 in Binary is 12 in Decimal = two digit wide output = 8 bits

See "Packed BCD"..
http://en.wikipedia.org/wiki/Binary-coded_decimal

Otherwise are you familiar with..
http://en.wikipedia.org/wiki/Karnaugh_map