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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | sylbir 201 | A mixed syllogism inference from a biconditional and an implication. |
| Theorem | sylibd 202 | A syllogism deduction. |
| Theorem | sylbid 203 | A syllogism deduction. |
| Theorem | sylibrd 204 | A syllogism deduction. |
| Theorem | sylbird 205 | A syllogism deduction. |
| Theorem | syl5ib 206 | A mixed syllogism inference from a nested implication and a biconditional. Useful for substituting an embedded antecedent with a definition. |
| Theorem | syl5ibr 207 | A mixed syllogism inference from a nested implication and a biconditional. |
| Theorem | syl5bi 208 | A mixed syllogism inference. |
| Theorem | syl5cbi 209 | A mixed syllogism inference. |
| Theorem | syl5bir 210 | A mixed syllogism inference. |
| Theorem | syl5cbir 211 | A mixed syllogism inference. |
| Theorem | syl6ib 212 | A mixed syllogism inference from a nested implication and a biconditional. |
| Theorem | syl6ibr 213 | A mixed syllogism inference from a nested implication and a biconditional. Useful for substituting an embedded consequent with a definition. |
| Theorem | syl6bi 214 | A mixed syllogism inference. |
| Theorem | syl6bir 215 | A mixed syllogism inference. |
| Theorem | syl7ib 216 | A mixed syllogism inference from a doubly nested implication and a biconditional. |
| Theorem | syl8ib 217 | A syllogism rule of inference. The second premise is used to replace the consequent of the first premise. |
| Theorem | 3imtr3 218 | A mixed syllogism inference, useful for removing a definition from both sides of an implication. |
| Theorem | 3imtr4 219 | A mixed syllogism inference, useful for applying a definition to both sides of an implication. |
| Theorem | con1bii 220 | A contraposition inference. |
| Theorem | con2bii 221 | A contraposition inference. |
| Logical disjunction and conjunction | ||
| Syntax | wo 222 | Extend wff definition to include disjunction ('or'). |
| Syntax | wa 223 | Extend wff definition to include conjunction ('and'). |
| Definition | df-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 |
| Definition | df-an 225 | Define conjunction (logical 'and'). Definition of [Margaris] p. 49. |
| Theorem | pm4.64 226 | Theorem *4.64 of [WhiteheadRussell] p. 120. |
| Theorem | pm2.54 227 | Theorem *2.54 of [WhiteheadRussell] p. 107. |
| Theorem | pm4.63 228 | Theorem *4.63 of [WhiteheadRussell] p. 120. |
| Theorem | dfor2 229 | Logical 'or' expressed in terms of implication only. Theorem *5.25 of [WhiteheadRussell] p. 124. |
| Theorem | ori 230 | Infer implication from disjunction. |
| Theorem | orri 231 | Infer implication from disjunction. |
| Theorem | ord 232 | Deduce implication from disjunction. |
| Theorem | orrd 233 | Deduce implication from disjunction. |
| Theorem | imor 234 | Implication in terms of disjunction. Theorem *4.6 of [WhiteheadRussell] p. 120. |
| Theorem | pm4.62 235 | Theorem *4.62 of [WhiteheadRussell] p. 120. |
| Theorem | pm4.66 236 | Theorem *4.66 of [WhiteheadRussell] p. 120. |
| Theorem | iman 237 | Express implication in terms of conjunction. Theorem 3.4(27) of [Stoll] p. 176. |
| Theorem | annim 238 | Express conjunction in terms of implication. |
| Theorem | pm4.61 239 | Theorem *4.61 of [WhiteheadRussell] p. 120. |
| Theorem | pm4.65 240 | Theorem *4.65 of [WhiteheadRussell] p. 120. |
| Theorem | pm4.67 241 | Theorem *4.67 of [WhiteheadRussell] p. 120. |
| Theorem | imnan 242 | Express implication in terms of conjunction. |
| Theorem | oridm 243 | Idempotent law for disjunction. Theorem *4.25 of [WhiteheadRussell] p. 117. |
| Theorem | pm4.25 244 | Theorem *4.25 of [WhiteheadRussell] p. 117. |
| Theorem | pm1.2 245 | Axiom *1.2 (Taut) of [WhiteheadRussell] p. 96. |
| Theorem | orcom 246 | Commutative law for disjunction. Theorem *4.31 of [WhiteheadRussell] p. 118. |
| Theorem | pm1.4 247 | Axiom *1.4 of [WhiteheadRussell] p. 96. |
| Theorem | pm2.62 248 | Theorem *2.62 of [WhiteheadRussell] p. 107. |
| Theorem | pm2.621 249 | Theorem *2.621 of [WhiteheadRussell] p. 107. |
| Theorem | pm2.68 250 | Theorem *2.68 of [WhiteheadRussell] p. 108. |
| Theorem | orel1 251 | Elimination of disjunction by denial of a disjunct. Theorem *2.55 of [WhiteheadRussell] p. 107. |
| Theorem | orel2 252 | Elimination of disjunction by denial of a disjunct. Theorem *2.56 of [WhiteheadRussell] p. 107. |
| Theorem | pm2.25 253 | Theorem *2.25 of [WhiteheadRussell] p. 104. |
| Theorem | pm2.53 254 | Theorem *2.53 of [WhiteheadRussell] p. 107. |
| Theorem | orbi2i 255 | Inference adding a left disjunct to both sides of a logical equivalence. |
| Theorem | orbi1i 256 | Inference adding a right disjunct to both sides of a logical equivalence. |
| Theorem | orbi12i 257 | Infer the disjunction of two equivalences. |
| Theorem | or12 258 | A rearrangement of disjuncts. |
| Theorem | pm1.5 259 | Axiom *1.5 (Assoc) of [WhiteheadRussell] p. 96. |
| Theorem | orass 260 | Associative law for disjunction. Theorem *4.33 of [WhiteheadRussell] p. 118. |
| Theorem | pm2.31 261 | Theorem *2.31 of [WhiteheadRussell] p. 104. |
| Theorem | pm2.32 262 | Theorem *2.32 of [WhiteheadRussell] p. 105. |
| Theorem | or23 263 | A rearrangement of disjuncts. |
| Theorem | or4 264 | Rearrangement of 4 disjuncts. |
| Theorem | or42 265 | Rearrangement of 4 disjuncts. |
| Theorem | orordi 266 | Distribution of disjunction over disjunction. |
| Theorem | orordir 267 | Distribution of disjunction over disjunction. |
| Theorem | olc 268 | Introduction of a disjunct. Axiom *1.3 of [WhiteheadRussell] p. 96. |
| Theorem | orc 269 | Introduction of a disjunct. Theorem *2.2 of [WhiteheadRussell] p. 104. |
| Theorem | orci 270 | Deduction introducing a disjunct. |
| Theorem | olci | |