# Why do the 2-SAT techniques do not work for 3-SAT?

i just want to know why the techniques we use to solve the 2-SAT problems cannot be used to solve the 3-SAT problem. So the techniques that i know that help solve 2-sat are the naive on where you just take one variable in the formula and give it a truth value and go on from there by deleting clauses where the variable is in it and so on. Why won't that work for 3-SAT so when i chose a variable and set it to true i do the same things that i would do for 2-SAT, shouldnt that also work? The second technique that i know that helps solve 2-SAT is where you create an implication graph from the formula with 2 implications per clause with the form being a$$\Rightarrow$$b, where a and b are literals. if i convert that to 3-SAT i could generate 3 implications per clause a$$\Rightarrow$$b$$\lor$$c where a,b and c are literals. why won't that algorithm work for 3-SAT the same way it works for 2-SAT?

• Have you tried your proposed algorithms on 3SAT? Jun 25 at 17:05
• Can you explain why your algorithms work for 2SAT? Do the same proofs carry on to 3SAT? Jun 25 at 17:05