1) Write down the clauses for ¬PHP32
Clauses:
{
{p11, p12}, {p21, p22}, {p31, p32},
{~p11, ~p21}, {~p11, ~p31}, {~p21, ~p31},
{~p12, ~p22}, {~p12, ~p32}, {~p22, ~p32}
}
2) What would be the set of clauses if p11 was True? Give a refutation for these clauses.
Clauses:
{
{p21, p22}, {p31, p32},
{~p21}, {~p31}, {~p21, ~p31},
{~p12, ~p22}, {~p12, ~p32}, {~p22, ~p32}
}<br
Refutation:
R1: {p21, p22}
R2: {~p21}
R3: {p22} resolved from R1 and R2
R4: {~p31}
R5: {p31, p32}
R6: {p32} resolved from R4 and R5
R7: {~p22, ~p32}
R8: {~p32} resolved from R3 and R7
R9: {} resolved from R6 and R8
3) What would be the set of clauses if p11 was False? Give a refutation for these clauses.
Clauses:
{
{p12}, {p21, p22}, {p31, p32},
{~p21, ~p31},
{~p12, ~p22}, {~p12, ~p32}, {~p22, ~p32}
}
Refutation:
R01: {~p12, ~p22}
R02: {p12}
R03: {~p22} resolved from R01 and R02
R04: {~p12, ~p32}
R05: {~p32} resolved from R02 and R04
R06: {p21, p22}
R07: {p21} resolved from R03 and R06
R08: {p31, p32}
R09: {p31} resolved from R05 and R08
R10: {~p21, ~p31}
R11: {~p21} resolved from R09 and R10
R12: {} resolved from R07 and R11
4) Figure out how to combine and modify these two proofs to give a refutation of ¬PHP32.
Clauses:
{
{p11, p12}, {p21, p22}, {p31, p32},
{~p11, ~p21}, {~p11, ~p31}, {~p21, ~p31},
{~p12, ~p22}, {~p12, ~p32}, {~p22, ~p32}
}
Refutation:
Part 1:
R1: {p21, p22}
R2: {~p11, ~p21}
R3: {~p11, p22} resolved from R1 and R2
R4: {~p11, ~p31}
R5: {p31, p32}
R6: {~p11, p32} resolved from R4 and R5
R7: {~p22, ~p32}
R8: {~p11, ~p32} resolved from R3 and R7
R9: {~p11} resolved from R6 and R8
Part 2:
R10: {~p12, ~p22}
R11: {p11, p12}
R12: {p11, ~p22} resolved from R10 and R11
R13: {~p12, ~p32}
R14: {p11, ~p32} resolved from R11 and R13
R15: {p21, p22}
R16: {p11, p21} resolved from R12 and R15
R17: {p31, p32}
R18: {p11, p31} resolved from R14 and R17
R19: {~p21, ~p31}
R20: {p11, ~p21} resolved from R18 and R19
R21: {p11} resolved from R16 and R20
Part 3:
R22: {} resolved from R9 and R21