## Video instructions and help with filling out and completing Form 843 Resolution

**Instructions and Help about Form 843 Resolution**

Hello youtubers my name is Raul and I'm a computer science student at the rapid University Nijmegen I'm currently following a course in semantics of logic programming and I would wish to share the subject material with you guys note that I'm not a native English speaker I'm Dutch so my English isn't perfect okay guys we first need a few definitions so you need to know what a clause is well a clause is a disjunction of literals so what is a literal well you have an atom a and atom can be either true or it can be false so a literal is an atom where it's a negated atom so we have an atom a or we have negated atom a so both of our normal atom is called a positive literal and a negative negative atom is called a negative literal so this are literals mm-hmm so when is something across then well we have to formula a implicates B or you say if a then B well it has the truth table let me first show you let me first make this well a truth table looks like this so we have 1 1 0 1 so well this is not a disjunction of literals because the disjunction is an or and literal is either a or not a well these are literals because B is a literal it's a normal atom and a is a literal it's a positive literal also a normal atom but this is in the way because we need nor so we need to write rewrite this that we only have ORS and positive or negative literals in our fiction so we can rewrite this then as negative a and positive B negative a and positive B normal be so we got a B 0 1 0 1 0 0 & 1 1 so I can show you that this is a truth right truth table because negative a is positive so or with 1 positive is always positive this is also positive I'm sorry for the penetrating well this is negative because negative becomes positive becomes negative and negative is negative so we get a 0 over here and we get a positive over here because when you got a positive inner or it's always positive so we got 1 1 0 1 hey it's all over here 1 1 0 1 so we have a clause over here um well there's an algorithm for making formulas into clauses but I'll cover that later on so I'll first give a definition of what a clause exactly is so we got some literals a 1 till a K and we got the literals b12 B L because they can have both different lengths so hmm it's a clause when we have a 1 or a K so the thing that's a 1 till a K are the positive literals and then we say negative B 1 till negative B L so they can have any length so this is a clause or to make things more complicated in logic programs they have an different notation well I'm not going to prove this but this is equivalent to this notation and that's be one till B L and a-one so I've got to or over here okay these are equivalents so from in logical programs they also write this I write this as a 1 comma till a K and then B 1 comma till B L but always keep in mind it's always the same so never worry and just think about how the normal Clause looks like and how they are logically equivalent and don't get scared because it looks a bit different this is also a clause so now you know what a clause is I am going to a few special cases of clauses we first start which where we only have one positive literal and an undefined amount of negative literals this is called a one clause and this is called the heads this code the till a whore Clause is also called a rule more on that later well you have another special kind of a clause and that's only with one positive literal and no till we don't have any negative literals and this is called effects well we also have the special kind where we have no hats and we only have a tail this is called a query Oracle we're be one till BL or sip goals you also have the special kind where both the head and the tail are empty this is also an indicator for the program to stop stop indication I will start with a small example afterwards so now I've told you something about clauses and horn clauses so what can we do with it well first I'll tell you something about you need to know something about propositional resolution propositional resolution well we got two clauses one is P and Q its effect because it's got no tail and we got one and it's called R and P so you see that P is over here and we see P over here profit propositional resolution states that you can make a new rule with it so we call this rule three and because P is over here at P over here it's a you know you can create a new rule called Q and R and with P delete it so we have no tail well for the administration we call it we put one and two behind it so we know what kind of rules we combines hit well I'll give some more examples so we got a rule Q and a rule of yeah and P we got the clothes QP this is a rule and we got P comma Q so we can create a new rule because P is over here and P this over here and note that we have.