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Statement List for Metamath Proof Explorer - 201-300 - Page 3 of 107
TypeLabelDescription
Statement
 
Theoremsylbir 201 A mixed syllogism inference from a biconditional and an implication.
|- (ps <-> ph)   &   |- (ps -> ch)   =>   |- (ph -> ch)
 
Theoremsylibd 202 A syllogism deduction.
|- (ph -> (ps -> ch))   &   |- (ph -> (ch <-> th))   =>   |- (ph -> (ps -> th))
 
Theoremsylbid 203 A syllogism deduction.
|- (ph -> (ps <-> ch))   &   |- (ph -> (ch -> th))   =>   |- (ph -> (ps -> th))
 
Theoremsylibrd 204 A syllogism deduction.
|- (ph -> (ps -> ch))   &   |- (ph -> (th <-> ch))   =>   |- (ph -> (ps -> th))
 
Theoremsylbird 205 A syllogism deduction.
|- (ph -> (ch <-> ps))   &   |- (ph -> (ch -> th))   =>   |- (ph -> (ps -> th))
 
Theoremsyl5ib 206 A mixed syllogism inference from a nested implication and a biconditional. Useful for substituting an embedded antecedent with a definition.
|- (ph -> (ps -> ch))   &   |- (th <-> ps)   =>   |- (ph -> (th -> ch))
 
Theoremsyl5ibr 207 A mixed syllogism inference from a nested implication and a biconditional.
|- (ph -> (ps -> ch))   &   |- (ps <-> th)   =>   |- (ph -> (th -> ch))
 
Theoremsyl5bi 208 A mixed syllogism inference.
|- (ph -> (ps <-> ch))   &   |- (th -> ps)   =>   |- (ph -> (th -> ch))
 
Theoremsyl5cbi 209 A mixed syllogism inference.
|- (ph -> (ps <-> ch))   &   |- (th -> ps)   =>   |- (th -> (ph -> ch))
 
Theoremsyl5bir 210 A mixed syllogism inference.
|- (ph -> (ps <-> ch))   &   |- (th -> ch)   =>   |- (ph -> (th -> ps))
 
Theoremsyl5cbir 211 A mixed syllogism inference.
|- (ph -> (ps <-> ch))   &   |- (th -> ch)   =>   |- (th -> (ph -> ps))
 
Theoremsyl6ib 212 A mixed syllogism inference from a nested implication and a biconditional.
|- (ph -> (ps -> ch))   &   |- (ch <-> th)   =>   |- (ph -> (ps -> th))
 
Theoremsyl6ibr 213 A mixed syllogism inference from a nested implication and a biconditional. Useful for substituting an embedded consequent with a definition.
|- (ph -> (ps -> ch))   &   |- (th <-> ch)   =>   |- (ph -> (ps -> th))
 
Theoremsyl6bi 214 A mixed syllogism inference.
|- (ph -> (ps <-> ch))   &   |- (ch -> th)   =>   |- (ph -> (ps -> th))
 
Theoremsyl6bir 215 A mixed syllogism inference.
|- (ph -> (ch <-> ps))   &   |- (ch -> th)   =>   |- (ph -> (ps -> th))
 
Theoremsyl7ib 216 A mixed syllogism inference from a doubly nested implication and a biconditional.
|- (ph -> (ps -> (ch -> th)))   &   |- (ta <-> ch)   =>   |- (ph -> (ps -> (ta -> th)))
 
Theoremsyl8ib 217 A syllogism rule of inference. The second premise is used to replace the consequent of the first premise.
|- (ph -> (ps -> (ch -> th)))   &   |- (th <-> ta)   =>   |- (ph -> (ps -> (ch -> ta)))
 
Theorem3imtr3 218 A mixed syllogism inference, useful for removing a definition from both sides of an implication.
|- (ph -> ps)   &   |- (ph <-> ch)   &   |- (ps <-> th)   =>   |- (ch -> th)
 
Theorem3imtr4 219 A mixed syllogism inference, useful for applying a definition to both sides of an implication.
|- (ph -> ps)   &   |- (ch <-> ph)   &   |- (th <-> ps)   =>   |- (ch -> th)
 
Theoremcon1bii 220 A contraposition inference.
|- (-. ph <-> ps)   =>   |- (-. ps <-> ph)
 
Theoremcon2bii 221 A contraposition inference.
|- (ph <-> -. ps)   =>   |- (ps <-> -. ph)
 
Logical disjunction and conjunction
 
Syntaxwo 222 Extend wff definition to include disjunction ('or').
wff (ph \/ ps)
 
Syntaxwa 223 Extend wff definition to include conjunction ('and').
wff (ph /\ ps)
 
Definitiondf-or 224 Define disjunction (logical 'or'). This is our first use of the biconditional connective in a definition; we use it in place of the traditional "<=def=>", which means the same thing, except that we can manipulate the biconditional connective directly in proofs rather than having to rely on an informal definition substitution rule. Note that if we mechanically substitute (-. ph -> ps) for (ph \/ ps), we end up with an instance of previously proved theorem pm4.2 170. This is the justification for the definition, along with the fact that it introduces a new symbol \/. Definition of [Margaris] p. 49.
|- ((ph \/ ps) <-> (-. ph -> ps))
 
Definitiondf-an 225 Define conjunction (logical 'and'). Definition of [Margaris] p. 49.
|- ((ph /\ ps) <-> -. (ph -> -. ps))
 
Theorempm4.64 226 Theorem *4.64 of [WhiteheadRussell] p. 120.
|- ((-. ph -> ps) <-> (ph \/ ps))
 
Theorempm2.54 227 Theorem *2.54 of [WhiteheadRussell] p. 107.
|- ((-. ph -> ps) -> (ph \/ ps))
 
Theorempm4.63 228 Theorem *4.63 of [WhiteheadRussell] p. 120.
|- (-. (ph -> -. ps) <-> (ph /\ ps))
 
Theoremdfor2 229 Logical 'or' expressed in terms of implication only. Theorem *5.25 of [WhiteheadRussell] p. 124.
|- ((ph \/ ps) <-> ((ph -> ps) -> ps))
 
Theoremori 230 Infer implication from disjunction.
|- (ph \/ ps)   =>   |- (-. ph -> ps)
 
Theoremorri 231 Infer implication from disjunction.
|- (-. ph -> ps)   =>   |- (ph \/ ps)
 
Theoremord 232 Deduce implication from disjunction.
|- (ph -> (ps \/ ch))   =>   |- (ph -> (-. ps -> ch))
 
Theoremorrd 233 Deduce implication from disjunction.
|- (ph -> (-. ps -> ch))   =>   |- (ph -> (ps \/ ch))
 
Theoremimor 234 Implication in terms of disjunction. Theorem *4.6 of [WhiteheadRussell] p. 120.
|- ((ph -> ps) <-> (-. ph \/ ps))
 
Theorempm4.62 235 Theorem *4.62 of [WhiteheadRussell] p. 120.
|- ((ph -> -. ps) <-> (-. ph \/ -. ps))
 
Theorempm4.66 236 Theorem *4.66 of [WhiteheadRussell] p. 120.
|- ((-. ph -> -. ps) <-> (ph \/ -. ps))
 
Theoremiman 237 Express implication in terms of conjunction. Theorem 3.4(27) of [Stoll] p. 176.
|- ((ph -> ps) <-> -. (ph /\ -. ps))
 
Theoremannim 238 Express conjunction in terms of implication.
|- ((ph /\ -. ps) <-> -. (ph -> ps))
 
Theorempm4.61 239 Theorem *4.61 of [WhiteheadRussell] p. 120.
|- (-. (ph -> ps) <-> (ph /\ -. ps))
 
Theorempm4.65 240 Theorem *4.65 of [WhiteheadRussell] p. 120.
|- (-. (-. ph -> ps) <-> (-. ph /\ -. ps))
 
Theorempm4.67 241 Theorem *4.67 of [WhiteheadRussell] p. 120.
|- (-. (-. ph -> -. ps) <-> (-. ph /\ ps))
 
Theoremimnan 242 Express implication in terms of conjunction.
|- ((ph -> -. ps) <-> -. (ph /\ ps))
 
Theoremoridm 243 Idempotent law for disjunction. Theorem *4.25 of [WhiteheadRussell] p. 117.
|- ((ph \/ ph) <-> ph)
 
Theorempm4.25 244 Theorem *4.25 of [WhiteheadRussell] p. 117.
|- (ph <-> (ph \/ ph))
 
Theorempm1.2 245 Axiom *1.2 (Taut) of [WhiteheadRussell] p. 96.
|- ((ph \/ ph) -> ph)
 
Theoremorcom 246 Commutative law for disjunction. Theorem *4.31 of [WhiteheadRussell] p. 118.
|- ((ph \/ ps) <-> (ps \/ ph))
 
Theorempm1.4 247 Axiom *1.4 of [WhiteheadRussell] p. 96.
|- ((ph \/ ps) -> (ps \/ ph))
 
Theorempm2.62 248 Theorem *2.62 of [WhiteheadRussell] p. 107.
|- ((ph \/ ps) -> ((ph -> ps) -> ps))
 
Theorempm2.621 249 Theorem *2.621 of [WhiteheadRussell] p. 107.
|- ((ph -> ps) -> ((ph \/ ps) -> ps))
 
Theorempm2.68 250 Theorem *2.68 of [WhiteheadRussell] p. 108.
|- (((ph -> ps) -> ps) -> (ph \/ ps))
 
Theoremorel1 251 Elimination of disjunction by denial of a disjunct. Theorem *2.55 of [WhiteheadRussell] p. 107.
|- (-. ph -> ((ph \/ ps) -> ps))
 
Theoremorel2 252 Elimination of disjunction by denial of a disjunct. Theorem *2.56 of [WhiteheadRussell] p. 107.
|- (-. ph -> ((ps \/ ph) -> ps))
 
Theorempm2.25 253 Theorem *2.25 of [WhiteheadRussell] p. 104.
|- (ph \/ ((ph \/ ps) -> ps))
 
Theorempm2.53 254 Theorem *2.53 of [WhiteheadRussell] p. 107.
|- ((ph \/ ps) -> (-. ph -> ps))
 
Theoremorbi2i 255 Inference adding a left disjunct to both sides of a logical equivalence.
|- (ph <-> ps)   =>   |- ((ch \/ ph) <-> (ch \/ ps))
 
Theoremorbi1i 256 Inference adding a right disjunct to both sides of a logical equivalence.
|- (ph <-> ps)   =>   |- ((ph \/ ch) <-> (ps \/ ch))
 
Theoremorbi12i 257 Infer the disjunction of two equivalences.
|- (ph <-> ps)   &   |- (ch <-> th)   =>   |- ((ph \/ ch) <-> (ps \/ th))
 
Theoremor12 258 A rearrangement of disjuncts.
|- ((ph \/ (ps \/ ch)) <-> (ps \/ (ph \/ ch)))
 
Theorempm1.5 259 Axiom *1.5 (Assoc) of [WhiteheadRussell] p. 96.
|- ((ph \/ (ps \/ ch)) -> (ps \/ (ph \/ ch)))
 
Theoremorass 260 Associative law for disjunction. Theorem *4.33 of [WhiteheadRussell] p. 118.
|- (((ph \/ ps) \/ ch) <-> (ph \/ (ps \/ ch)))
 
Theorempm2.31 261 Theorem *2.31 of [WhiteheadRussell] p. 104.
|- ((ph \/ (ps \/ ch)) -> ((ph \/ ps) \/ ch))
 
Theorempm2.32 262 Theorem *2.32 of [WhiteheadRussell] p. 105.
|- (((ph \/ ps) \/ ch) -> (ph \/ (ps \/ ch)))
 
Theoremor23 263 A rearrangement of disjuncts.
|- (((ph \/ ps) \/ ch) <-> ((ph \/ ch) \/ ps))
 
Theoremor4 264 Rearrangement of 4 disjuncts.
|- (((ph \/ ps) \/ (ch \/ th)) <-> ((ph \/ ch) \/ (ps \/ th)))
 
Theoremor42 265 Rearrangement of 4 disjuncts.
|- (((ph \/ ps) \/ (ch \/ th)) <-> ((ph \/ ch) \/ (th \/ ps)))
 
Theoremorordi 266 Distribution of disjunction over disjunction.
|- ((ph \/ (ps \/ ch)) <-> ((ph \/ ps) \/ (ph \/ ch)))
 
Theoremorordir 267 Distribution of disjunction over disjunction.
|- (((ph \/ ps) \/ ch) <-> ((ph \/ ch) \/ (ps \/ ch)))
 
Theoremolc 268 Introduction of a disjunct. Axiom *1.3 of [WhiteheadRussell] p. 96.
|- (ph -> (ps \/ ph))
 
Theoremorc 269 Introduction of a disjunct. Theorem *2.2 of [WhiteheadRussell] p. 104.
|- (ph -> (ph \/ ps))
 
Theoremorci 270 Deduction introducing a disjunct.
|- ph   =>   |- (ph \/ ps)
 
Theoremolci 271 Deduction introducing a disjunct.