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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | 19.23bi 1101 | Inference from Theorem 19.23 of [Margaris] p. 90. |
| Theorem | 19.23ad 1102 | Deduction from Theorem 19.23 of [Margaris] p. 90. |
| Theorem | 19.26 1103 | Theorem 19.26 of [Margaris] p. 90. Also Theorem *10.22 of [WhiteheadRussell] p. 119. |
| Theorem | 19.26-2 1104 | Theorem 19.26 of [Margaris] p. 90 with two quantifiers. |
| Theorem | 19.27 1105 | Theorem 19.27 of [Margaris] p. 90. |
| Theorem | 19.28 1106 | Theorem 19.28 of [Margaris] p. 90. |
| Theorem | 19.29 1107 | Theorem 19.29 of [Margaris] p. 90. |
| Theorem | 19.29r 1108 | Variation of Theorem 19.29 of [Margaris] p. 90. |
| Theorem | 19.29r2 1109 | Variation of Theorem 19.29 of [Margaris] p. 90 with double quantification. |
| Theorem | 19.29x 1110 | Variation of Theorem 19.29 of [Margaris] p. 90 with mixed quantification. |
| Theorem | 19.35 1111 | Theorem 19.35 of [Margaris] p. 90. This theorem is useful for moving an implication (in the form of the right-hand side) into the scope of a single existential quantifier. |
| Theorem | 19.35i 1112 | Inference from Theorem 19.35 of [Margaris] p. 90. |
| Theorem | 19.35ri 1113 | Inference from Theorem 19.35 of [Margaris] p. 90. |
| Theorem | 19.36 1114 | Theorem 19.36 of [Margaris] p. 90. |
| Theorem | 19.36i 1115 | Inference from Theorem 19.36 of [Margaris] p. 90. |
| Theorem | 19.37 1116 | Theorem 19.37 of [Margaris] p. 90. |
| Theorem | 19.38 1117 | Theorem 19.38 of [Margaris] p. 90. |
| Theorem | 19.39 1118 | Theorem 19.39 of [Margaris] p. 90. |
| Theorem | 19.24 1119 | Theorem 19.24 of [Margaris] p. 90. |
| Theorem | 19.25 1120 | Theorem 19.25 of [Margaris] p. 90. |
| Theorem | 19.30 1121 | Theorem 19.30 of [Margaris] p. 90. |
| Theorem | 19.32 1122 | Theorem 19.32 of [Margaris] p. 90. |
| Theorem | 19.31 1123 | Theorem 19.31 of [Margaris] p. 90. |
| Theorem | 19.43 1124 | Theorem 19.43 of [Margaris] p. 90. |
| Theorem | 19.44 1125 | Theorem 19.44 of [Margaris] p. 90. |
| Theorem | 19.45 1126 | Theorem 19.45 of [Margaris] p. 90. |
| Theorem | 19.33 1127 | Theorem 19.33 of [Margaris] p. 90. |
| Theorem | 19.33b 1128 | The antecedent provides a condition implying the converse of 19.33 1127. Compare Theorem 19.33 of [Margaris] p. 90. |
| Theorem | 19.34 1129 | Theorem 19.34 of [Margaris] p. 90. |
| Theorem | 19.40 1130 | Theorem 19.40 of [Margaris] p. 90. |
| Theorem | 19.41 1131 | Theorem 19.41 of [Margaris] p. 90. |
| Theorem | 19.42 1132 | Theorem 19.42 of [Margaris] p. 90. |
| Theorem | alrot4 1133 | Rotate 4 universal quantifiers twice. |
| Theorem | excom13 1134 | Swap 1st and 3rd existential quantifiers. |
| Theorem | exrot3 1135 | Rotate existential quantifiers. |
| Theorem | exrot4 1136 | Rotate existential quantifiers twice. |
| Theorem | nex 1137 | Generalization rule for negated wff. |
| Theorem | nexd 1138 | Deduction for generalization rule for negated wff. |
| Theorem | hbim1 1139 | A closed form of hbim 1043. |
| Theorem | albid 1140 | Formula-building rule for universal quantifier (deduction rule). |
| Theorem | exbid 1141 | Formula-building rule for existential quantifier (deduction rule). |
| Theorem | exan 1142 | Place a conjunct in the scope of an existential quantifier. |
| Theorem | albi 1143 | Split a biconditional and distribute quantifier. |
| Theorem | 2albi 1144 | Split a biconditional and distribute 2 quantifiers. |
| Theorem | hbnd 1145 | Deduction form of bound-variable hypothesis builder hbn 1040. |
| Theorem | hbimd 1146 | Deduction form of bound-variable hypothesis builder hbim 1043. |
| Theorem | hband 1147 | Deduction form of bound-variable hypothesis builder hban 1045. |
| Theorem | hbbid 1148 | Deduction form of bound-variable hypothesis builder hbbi 1046. |
| Theorem | hbald 1149 | Deduction form of bound-variable hypothesis builder hbal 1041. |
| Theorem | hbexd 1150 | Deduction form of bound-variable hypothesis builder hbex 1042. |
| Theorem | 19.21t 1151 | Closed form of Theorem 19.21 of [Margaris] p. 90. |
| Theorem | 19.23t 1152 | Closed form of Theorem 19.23 of [Margaris] p. 90. |
| Theorem | exintr 1153 | Introduce a conjunct in the scope of an existential quantifier. |
| Theorem | exintrbi 1154 | Add/remove a conjunct in the scope of an existential quantifier. (Contributed by Raph Levien, 3-Jul-2006.) |
| Theorem | aaan 1155 | Rearrange universal quantifiers. |
| Theorem | eeor 1156 | Rearrange existential quantifiers. |
| Theorem | qexmid 1157 | Quantified "excluded middle." Exercise 9.2a of Boolos, p. 111, Computability and Logic. |
| Equality | ||
| Theorem | ax9o 1158 |
Show that the original axiom ax-9o 1159 can be derived from ax-9 1001
and
others. See ax9 1160 for the rederivation of ax-9 1001
from ax-9o 1159.
This theorem should not be referenced in any proof. Instead, use ax-9o 1159 below so that uses of ax-9o 1159 can be more easily identified. |
| Axiom | ax-9o 1159 |
A variant of ax-9 1001. Axiom scheme C10' in [Megill] p. 448 (p. 16 of the
preprint).
This axiom is redundant, as shown by theorem ax9o 1158. |
| Theorem | ax9 1160 |
Rederivation of axiom ax-9 1001 from the orginal version, ax-9o 1159.
See ax9o 1158 for the derivation of ax-9o 1159 from ax-9 1001. Lemma L18 in
[Megill] p. 446 (p. 14 of the preprint).
This theorem should not be referenced in any proof. Instead, use ax-9 1001 above so that uses of ax-9 1001 can be more easily identified. |
| Theorem | a9e 1161 | At least one individual exists. This is not a theorem of free logic, which is sound in empty domains. For such a logic, we would add this theorem as an axiom of set theory (Axiom 0 of [Kunen] p. 10). In the system consisting of ax-5 996 through ax-14 1006 and ax-17 1007, all axioms other than ax-9 1001 are believed to be theorems of free logic, although the system without ax-9 1001 is probably not complete in free logic. |
| Theorem | equid 1162 | Identity law for equality (reflexivity). Lemma 6 of [Tarski] p. 68. This is often an axiom of equality in textbook systems, but we don't need it as an axiom since it can be proved from our other axioms (although the proof, as you can see below, is not as obvious as you might think). This proof uses only axioms without distinct variable conditions and thus requires no dummy variables. A simpler proof, similar to Tarki's, is possible if we make use of ax-17 1007; see the proof of equid1 1307. See equidALT 1163 for an alternate proof. |
| Theorem | equidALT 1163 | Identity law for equality (reflexivity). Lemma 6 of [Tarski] p. 68. Alternate proof of equid 1162 directly from equality axioms ax-9 1001 and ax-12 1004. |
| Theorem | stdpc6 1164 | One of the two equality axioms of standard predicate calculus, called reflexivity of equality. (The other one is stdpc7 1217.) Axiom 6 of [Mendelson] p. 95. Mendelson doesn't say why he prepended the redundant quantifier, but it was probably to be compatible with free logic (which is valid in the empty domain). |
| Theorem | equcomi 1165 | Commutative law for equality. Lemma 7 of [Tarski] p. 69. |
| Theorem | equcom 1166 | Commutative law for equality. |
| Theorem | equcoms 1167 | An inference commuting equality in antecedent. Used to eliminate the need for a syllogism. |
| Theorem | equtr 1168 | A transitive law for equality. |
| Theorem | equtrr 1169 | A transitive law for equality. Lemma L17 in [Megill] p. 446 (p. 14 of the preprint). |
| Theorem | equtr2 1170 | A transitive law for equality. |
| Theorem | equequ1 1171 | An equivalence law for equality. |
| Theorem | equequ2 1172 | An equivalence law for equality. |
| Theorem | elequ1 1173 | An identity law for the non-logical predicate. |
| Theorem | elequ2 1174 | An identity law for the non-logical predicate. |
| Theorem | ax11i 1175 |
Inference that has ax-11 1003 (without |
| Axioms ax-10 and ax-11 | ||
| Theorem | ax10o 1176 |
Show that ax-10o 1177 can be derived from ax-10 1002. An open problem is
whether this theorem can be derived from ax-10 1002 and the others when
ax-11 1003 is replaced with ax-11o 1255. See theorem ax10 1178
for the
rederivation of ax-10 1002 from ax10o 1176.
This theorem should not be referenced in any proof. Instead, use ax-10o 1177 below so that uses of ax-10o 1177 can be more easily identified. |
| Axiom | ax-10o 1177 |
Axiom ax-10o 1177 ("o" for "old") was the
original version of ax-10 1002,
before it was discovered (in May 2008) that the shorter ax-10 1002 could
replace it. It appears as Axiom scheme C11' in [Megill] p. 448 (p. 16
of the preprint).
This axiom is redundant, as shown by theorem ax10o 1176. |
| Theorem | ax10 1178 |
Rederivation of ax-10 1002 from original version ax-10o 1177. See theorem
ax10o 1176 for the derivation of ax-10o 1177 from ax-10 1002.
This theorem should not be referenced in any proof. Instead, use ax-10 1002 above so that uses of ax-10 1002 can be more easily identified. |
| Theorem | alequcom 1179 |
Commutation law for identical variable specifiers. The antecedent and
consequent are true when |
| Theorem | alequcoms 1180 | A commutation rule for identical variable specifiers. |
| Theorem | nalequcoms 1181 | A commutation rule for distinct variable specifiers. |
| Theorem | hbae 1182 | All variables are effectively bound in an identical variable specifier. |
| Theorem | hbaes 1183 | Rule that applies hbae 1182 to antecedent. |
| Theorem | hbnae 1184 | All variables are effectively bound in a distinct variable specifier. Lemma L19 in [Megill] p. 446 (p. 14 of the preprint). |
| Theorem | hbnaes 1185 | Rule that applies hbnae 1184 to antecedent. |
| Theorem | equs3 1186 | Lemma used in proofs of substitution properties. |
| Theorem | equs4 1187 | Lemma used in proofs of substitution properties. |
| Theorem | equsal 1188 | A useful equivalence related to substitution. |
| Theorem | equsex 1189 | A useful equivalence related to substitution. |
| Theorem | dvelimfALT 1190 | Proof of dvelimf 1288 without using ax-11 1003. See dvelimALT 1392 for a proof (of the distinct variable version dvelim 1391) that doesn't require ax-10 1002. |
| Theorem | dral1 1191 | Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of [Megill] p. 448 (p. 16 of preprint). |
| Theorem | dral2 1192 | Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of [Megill] p. 448 (p. 16 of preprint). |
| Theorem | drex1 1193 | Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of [Megill] p. 448 (p. 16 of preprint). |
| Theorem | drex2 1194 | Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of [Megill] p. 448 (p. 16 of preprint). |
| Theorem | a4imt 1195 | Closed theorem form of a4im 1196. |
| Theorem | a4im 1196 | Specialization, using implicit substitition. Compare Lemma 14 of [Tarski] p. 70. The a4im 1196 series of theorems requires that only one direction of the substitution hypothesis hold. |
| Theorem | a4ime 1197 | Existential introduction, using implicit substitition. Compare Lemma 14 of [Tarski] p. 70. |
| Theorem | a4imed 1198 | Deduction version of a4ime 1197. |
| Theorem | cbv1 1199 | Rule used to change bound variables, using implicit substitition. |
| Theorem | cbv2 1200 | Rule used to change bound variables, using implicit substitition. |
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