HomeHome Metamath Proof Explorer
Theorem List (p. 382 of 426)
< Previous  Next >
Browser slow? Try the
Unicode version.

Mirrors  >  Metamath Home Page  >  MPE Home Page  >  Theorem List Contents  >  Recent Proofs       This page: Page List

Color key:    Metamath Proof Explorer  Metamath Proof Explorer
(1-27775)
  Hilbert Space Explorer  Hilbert Space Explorer
(27776-29300)
  Users' Mathboxes  Users' Mathboxes
(29301-42551)
 

Theorem List for Metamath Proof Explorer - 38101-38200   *Has distinct variable group(s)
TypeLabelDescription
Statement
 
Theoremaxfrege8 38101 Swap antecedents. Identical to pm2.04 90. This demonstrates that Axiom 8 of [Frege1879] p. 35 is redundant.

Proof follows closely proof of pm2.04 90 in http://us.metamath.org/mmsolitaire/pmproofs.txt, but in the style of Frege's 1879 work. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.) (Proof modification is discouraged.)

 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ps  ->  ( ph  ->  ch ) ) )
 
Theoremfrege7 38102 A closed form of syl6 35. The first antecedent is used to replace the consequent of the second antecedent. Proposition 7 of [Frege1879] p. 34. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ps )  ->  ( ( ch  ->  ( th  ->  ph ) ) 
 ->  ( ch  ->  ( th  ->  ps ) ) ) )
 
Axiomax-frege8 38103 Swap antecedents. If two conditions have a proposition as a consequence, their order is immaterial. Third axiom of Frege's 1879 work but identical to pm2.04 90 which can be proved from only ax-mp 5, ax-frege1 38084, and ax-frege2 38085. (Redundant) Axiom 8 of [Frege1879] p. 35. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ps  ->  ( ph  ->  ch ) ) )
 
Theoremfrege26 38104 Identical to idd 24. Proposition 26 of [Frege1879] p. 42. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( ph  ->  ( ps  ->  ps ) )
 
Theoremfrege27 38105 We cannot (at the same time) affirm  ph and deny 
ph. Identical to id 22. Proposition 27 of [Frege1879] p. 43. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( ph  ->  ph )
 
Theoremfrege9 38106 Closed form of syl 17 with swapped antecedents. This proposition differs from frege5 38094 only in an unessential way. Identical to imim1 83. Proposition 9 of [Frege1879] p. 35. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ps )  ->  ( ( ps  ->  ch )  ->  ( ph  ->  ch ) ) )
 
Theoremfrege12 38107 A closed form of com23 86. Proposition 12 of [Frege1879] p. 37. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  th )
 ) )  ->  ( ph  ->  ( ch  ->  ( ps  ->  th )
 ) ) )
 
Theoremfrege11 38108 Elimination of a nested antecedent as a partial converse of ja 173. If the proposition that  ps takes place or  ph does not is a sufficient condition for  ch, then  ps by itself is a sufficient condition for  ch. Identical to jarr 106. Proposition 11 of [Frege1879] p. 36. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( ph  ->  ps )  ->  ch )  ->  ( ps  ->  ch )
 )
 
Theoremfrege24 38109 Closed form for a1d 25. Deduction introducing an embedded antecedent. Identical to rp-frege24 38091 which was proved without relying on ax-frege8 38103. Proposition 24 of [Frege1879] p. 42. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ps )  ->  ( ph  ->  ( ch  ->  ps ) ) )
 
Theoremfrege16 38110 A closed form of com34 91. Proposition 16 of [Frege1879] p. 38. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  ( th  ->  ta ) ) ) )  ->  ( ph  ->  ( ps  ->  ( th  ->  ( ch  ->  ta ) ) ) ) )
 
Theoremfrege25 38111 Closed form for a1dd 50. Proposition 25 of [Frege1879] p. 42. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ph  ->  ( ps  ->  ( th  ->  ch )
 ) ) )
 
Theoremfrege18 38112 Closed form of a syllogism followed by a swap of antecedents. Proposition 18 of [Frege1879] p. 39. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ( th  ->  ph )  ->  ( ps  ->  ( th  ->  ch )
 ) ) )
 
Theoremfrege22 38113 A closed form of com45 97. Proposition 22 of [Frege1879] p. 41. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  ( th  ->  ( ta  ->  et ) ) ) ) )  ->  ( ph  ->  ( ps  ->  ( ch  ->  ( ta  ->  ( th  ->  et )
 ) ) ) ) )
 
Theoremfrege10 38114 Result commuting antecedents within an antecedent. Proposition 10 of [Frege1879] p. 36. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( ph  ->  ( ps  ->  ch )
 )  ->  th )  ->  ( ( ps  ->  (
 ph  ->  ch ) )  ->  th ) )
 
Theoremfrege17 38115 A closed form of com3l 89. Proposition 17 of [Frege1879] p. 39. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  th )
 ) )  ->  ( ps  ->  ( ch  ->  (
 ph  ->  th ) ) ) )
 
Theoremfrege13 38116 A closed form of com3r 87. Proposition 13 of [Frege1879] p. 37. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  th )
 ) )  ->  ( ch  ->  ( ph  ->  ( ps  ->  th )
 ) ) )
 
Theoremfrege14 38117 Closed form of a deduction based on com3r 87. Proposition 14 of [Frege1879] p. 37. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  ( th  ->  ta ) ) ) )  ->  ( ph  ->  ( th  ->  ( ps  ->  ( ch  ->  ta ) ) ) ) )
 
Theoremfrege19 38118 A closed form of syl6 35. Proposition 19 of [Frege1879] p. 39. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ( ch  ->  th )  ->  ( ph  ->  ( ps  ->  th )
 ) ) )
 
Theoremfrege23 38119 Syllogism followed by rotation of three antecedents. Proposition 23 of [Frege1879] p. 42. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  th )
 ) )  ->  (
 ( ta  ->  ph )  ->  ( ps  ->  ( ch  ->  ( ta  ->  th ) ) ) ) )
 
Theoremfrege15 38120 A closed form of com4r 94. Proposition 15 of [Frege1879] p. 38. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  ( th  ->  ta ) ) ) )  ->  ( th  ->  ( ph  ->  ( ps  ->  ( ch  ->  ta ) ) ) ) )
 
Theoremfrege21 38121 Replace antecedent in antecedent. Proposition 21 of [Frege1879] p. 40. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( ph  ->  ps )  ->  ch )  ->  ( ( ph  ->  th )  ->  ( ( th  ->  ps )  ->  ch )
 ) )
 
Theoremfrege20 38122 A closed form of syl8 76. Proposition 20 of [Frege1879] p. 40. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ( ch  ->  th )
 ) )  ->  (
 ( th  ->  ta )  ->  ( ph  ->  ( ps  ->  ( ch  ->  ta ) ) ) ) )
 
20.27.3.4  _Begriffsschrift_ Chapter II Implication and Negation
 
Theoremaxfrege28 38123 Contraposition. Identical to con3 149. Theorem *2.16 of [WhiteheadRussell] p. 103. (Contributed by RP, 24-Dec-2019.)
 |-  (
 ( ph  ->  ps )  ->  ( -.  ps  ->  -.  ph ) )
 
Axiomax-frege28 38124 Contraposition. Identical to con3 149. Theorem *2.16 of [WhiteheadRussell] p. 103. Axiom 28 of [Frege1879] p. 43. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  (
 ( ph  ->  ps )  ->  ( -.  ps  ->  -.  ph ) )
 
Theoremfrege29 38125 Closed form of con3d 148. Proposition 29 of [Frege1879] p. 43. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ph  ->  ( -.  ch 
 ->  -.  ps ) ) )
 
Theoremfrege30 38126 Commuted, closed form of con3d 148. Proposition 30 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ps  ->  ( -.  ch 
 ->  -.  ph ) ) )
 
Theoremaxfrege31 38127 Identical to notnotr 125. Axiom 31 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.)
 |-  ( -.  -.  ph  ->  ph )
 
Axiomax-frege31 38128  ph cannot be denied and (at the same time )  -.  -.  ph affirmed. Duplex negatio affirmat. The denial of the denial is affirmation. Identical to notnotr 125. Axiom 31 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  ( -.  -.  ph  ->  ph )
 
Theoremfrege32 38129 Deduce con1 143 from con3 149. Proposition 32 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( -.  ph  ->  ps )  ->  ( -.  ps  ->  -.  -.  ph ) )  ->  ( ( -.  ph  ->  ps )  ->  ( -.  ps  ->  ph ) ) )
 
Theoremfrege33 38130 If  ph or  ps takes place, then  ps or  ph takes place. Identical to con1 143. Proposition 33 of [Frege1879] p. 44. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ps )  ->  ( -.  ps 
 ->  ph ) )
 
Theoremfrege34 38131 If as a conseqence of the occurence of the circumstance  ph, when the obstacle  ps is removed,  ch takes place, then from the circumstance that  ch does not take place while  ph occurs the occurence of the obstacle  ps can be inferred. Closed form of con1d 139. Proposition 34 of [Frege1879] p. 45. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( -. 
 ps  ->  ch ) )  ->  ( ph  ->  ( -.  ch 
 ->  ps ) ) )
 
Theoremfrege35 38132 Commuted, closed form of con1d 139. Proposition 35 of [Frege1879] p. 45. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( -. 
 ps  ->  ch ) )  ->  ( -.  ch  ->  ( ph  ->  ps ) ) )
 
Theoremfrege36 38133 The case in which  ps is denied,  -.  ph is affirmed, and  ph is affirmed does not occur. If  ph occurs, then (at least) one of the two,  ph or  ps, takes place (no matter what  ps might be). Identical to pm2.24 121. Proposition 36 of [Frege1879] p. 45. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( ph  ->  ( -.  ph  ->  ps ) )
 
Theoremfrege37 38134 If  ch is a necessary consequence of the occurrence of 
ps or  ph, then  ch is a necessary consequence of  ph alone. Similar to a closed form of orcs 409. Proposition 37 of [Frege1879] p. 46. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( -.  ph  ->  ps )  ->  ch )  ->  ( ph  ->  ch )
 )
 
Theoremfrege38 38135 Identical to pm2.21 120. Proposition 38 of [Frege1879] p. 46. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( -.  ph  ->  ( ph  ->  ps ) )
 
Theoremfrege39 38136 Syllogism between pm2.18 122 and pm2.24 121. Proposition 39 of [Frege1879] p. 46. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ph )  ->  ( -.  ph 
 ->  ps ) )
 
Theoremfrege40 38137 Anything implies pm2.18 122. Proposition 40 of [Frege1879] p. 46. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( -.  ph  ->  ( ( -.  ps  ->  ps )  ->  ps ) )
 
Theoremaxfrege41 38138 Identical to notnot 136. Axiom 41 of [Frege1879] p. 47. (Contributed by RP, 24-Dec-2019.)
 |-  ( ph  ->  -.  -.  ph )
 
Axiomax-frege41 38139 The affirmation of  ph denies the denial of  ph. Identical to notnot 136. Axiom 41 of [Frege1879] p. 47. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  ( ph  ->  -.  -.  ph )
 
Theoremfrege42 38140 Not not id 22. Proposition 42 of [Frege1879] p. 47. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  -.  -.  ( ph  ->  ph )
 
Theoremfrege43 38141 If there is a choice only between  ph and  ph, then  ph takes place. Identical to pm2.18 122. Proposition 43 of [Frege1879] p. 47. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ph )  ->  ph )
 
Theoremfrege44 38142 Similar to a commuted pm2.62 425. Proposition 44 of [Frege1879] p. 47. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ps )  ->  ( ( ps  ->  ph )  ->  ph )
 )
 
Theoremfrege45 38143 Deduce pm2.6 182 from con1 143. Proposition 45 of [Frege1879] p. 47. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( -.  ph  ->  ps )  ->  ( -.  ps  ->  ph ) ) 
 ->  ( ( -.  ph  ->  ps )  ->  (
 ( ph  ->  ps )  ->  ps ) ) )
 
Theoremfrege46 38144 If  ps holds when  ph occurs as well as when  ph does not occur, then  ps holds. If  ps or  ph occurs and if the occurences of  ph has  ps as a necessary consequence, then  ps takes place. Identical to pm2.6 182. Proposition 46 of [Frege1879] p. 48. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ps )  ->  ( ( ph  ->  ps )  ->  ps )
 )
 
Theoremfrege47 38145 Deduce consequence follows from either path implied by a disjunction. If  ph, as well as  ps is sufficient condition for  ch and  ps or  ph takes place, then the proposition  ch holds. Proposition 47 of [Frege1879] p. 48. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ps )  ->  ( ( ps  ->  ch )  ->  (
 ( ph  ->  ch )  ->  ch ) ) )
 
Theoremfrege48 38146 Closed form of syllogism with internal disjunction. If  ph is a sufficient condition for the occurence of  ch or 
ps and if  ch, as well as  ps, is a sufficient condition for  th, then  ph is a sufficient condition for 
th. See application in frege101 38258. Proposition 48 of [Frege1879] p. 49. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( -. 
 ps  ->  ch ) )  ->  ( ( ch  ->  th )  ->  ( ( ps  ->  th )  ->  ( ph  ->  th ) ) ) )
 
Theoremfrege49 38147 Closed form of deduction with disjunction. Proposition 49 of [Frege1879] p. 49. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( -.  ph  ->  ps )  ->  ( ( ph  ->  ch )  ->  (
 ( ps  ->  ch )  ->  ch ) ) )
 
Theoremfrege50 38148 Closed form of jaoi 394. Proposition 50 of [Frege1879] p. 49. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ps )  ->  ( ( ch  ->  ps )  ->  ( ( -.  ph  ->  ch )  ->  ps ) ) )
 
Theoremfrege51 38149 Compare with jaod 395. Proposition 51 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  ->  ( ps 
 ->  ch ) )  ->  ( ( th  ->  ch )  ->  ( ph  ->  ( ( -.  ps  ->  th )  ->  ch )
 ) ) )
 
20.27.3.5  _Begriffsschrift_ Chapter II with logical equivalence

Here we leverage df-ifp 1013 to partition a wff into two that are disjoint with the selector wff.

Thus if we are given  |-  ( ph  <-> if- ( ps ,  ch ,  th )
) then we replace the concept (illegal in our notation )  ( ph `  ps ) with if- ( ps ,  ch ,  th ) to reason about the values of the "function." Likewise, we replace the similarly illegal concept  A. ps ph with  ( ch  /\ 
th ).

 
Theoremaxfrege52a 38150 Justification for ax-frege52a 38151. (Contributed by RP, 17-Apr-2020.)
 |-  (
 ( ph  <->  ps )  ->  (if- ( ph ,  th ,  ch )  -> if- ( ps ,  th ,  ch ) ) )
 
Axiomax-frege52a 38151 The case when the content of 
ph is identical with the content of  ps and in which a proposition controlled by an element for which we substitute the content of 
ph is affirmed ( in this specific case the identity logical funtion ) and the same proposition, this time where we substituted the content of 
ps, is denied does not take place. Part of Axiom 52 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  (
 ( ph  <->  ps )  ->  (if- ( ph ,  th ,  ch )  -> if- ( ps ,  th ,  ch ) ) )
 
Theoremfrege52aid 38152 The case when the content of 
ph is identical with the content of  ps and in which  ph is affirmed and  ps is denied does not take place. Identical to biimp 205. Part of Axiom 52 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  <->  ps )  ->  ( ph  ->  ps ) )
 
Theoremfrege53aid 38153 Specialization of frege53a 38154. Proposition 53 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( ph  ->  ( ( ph  <->  ps )  ->  ps ) )
 
Theoremfrege53a 38154 Lemma for frege55a 38162. Proposition 53 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (if- ( ph ,  th ,  ch )  ->  ( (
 ph 
 <->  ps )  -> if- ( ps ,  th ,  ch ) ) )
 
Theoremaxfrege54a 38155 Justification for ax-frege54a 38156. Identical to biid 251. (Contributed by RP, 24-Dec-2019.)
 |-  ( ph 
 <-> 
 ph )
 
Axiomax-frege54a 38156 Reflexive equality of wffs. The content of  ph is identical with the content of  ph. Part of Axiom 54 of [Frege1879] p. 50. Identical to biid 251. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  ( ph 
 <-> 
 ph )
 
Theoremfrege54cor0a 38157 Synonym for logical equivalence. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ps  <->  ph )  <-> if- ( ps ,  ph ,  -.  ph ) )
 
Theoremfrege54cor1a 38158 Reflexive equality. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |- if- ( ph ,  ph ,  -.  ph )
 
Theoremfrege55aid 38159 Lemma for frege57aid 38166. Core proof of Proposition 55 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.)
 |-  (
 ( ph  <->  ps )  ->  ( ps 
 <-> 
 ph ) )
 
Theoremfrege55lem1a 38160 Necessary deduction regarding substitution of value in equality. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ta  -> if- ( ps ,  ph ,  -.  ph ) )  ->  ( ta  ->  ( ps  <->  ph ) ) )
 
Theoremfrege55lem2a 38161 Core proof of Proposition 55 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  <->  ps )  -> if- ( ps ,  ph ,  -.  ph ) )
 
Theoremfrege55a 38162 Proposition 55 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  <->  ps )  -> if- ( ps ,  ph ,  -.  ph ) )
 
Theoremfrege55cor1a 38163 Proposition 55 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  <->  ps )  ->  ( ps 
 <-> 
 ph ) )
 
Theoremfrege56aid 38164 Lemma for frege57aid 38166. Proposition 56 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( ph  <->  ps )  ->  ( ph  ->  ps ) )  ->  ( ( ps  <->  ph )  ->  ( ph  ->  ps ) ) )
 
Theoremfrege56a 38165 Proposition 56 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ( ph  <->  ps )  ->  (if- ( ph ,  ch ,  th )  -> if- ( ps ,  ch ,  th ) ) )  ->  ( ( ps  <->  ph )  ->  (if- ( ph ,  ch ,  th )  -> if- ( ps ,  ch ,  th ) ) ) )
 
Theoremfrege57aid 38166 This is the all imporant formula which allows us to apply Frege-style definitions and explore their consequences. A closed form of biimpri 218. Proposition 57 of [Frege1879] p. 51. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  <->  ps )  ->  ( ps  ->  ph ) )
 
Theoremfrege57a 38167 Analogue of frege57aid 38166. Proposition 57 of [Frege1879] p. 51. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( ph  <->  ps )  ->  (if- ( ps ,  ch ,  th )  -> if- ( ph ,  ch ,  th )
 ) )
 
Theoremaxfrege58a 38168 Identical to anifp 1020. Justification for ax-frege58a 38169. (Contributed by RP, 28-Mar-2020.)
 |-  (
 ( ps  /\  ch )  -> if- ( ph ,  ps ,  ch ) )
 
Axiomax-frege58a 38169 If  A. x ph is affirmed,  [
y  /  x ] ph cannot be denied. Identical to stdpc4 2353. Axiom 58 of [Frege1879] p. 51. (Contributed by RP, 28-Mar-2020.) (New usage is discouraged.)
 |-  (
 ( ps  /\  ch )  -> if- ( ph ,  ps ,  ch ) )
 
Theoremfrege58acor 38170 Lemma for frege59a 38171. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 ( ( ps  ->  ch )  /\  ( th  ->  ta ) )  ->  (if- ( ph ,  ps ,  th )  -> if- ( ph ,  ch ,  ta )
 ) )
 
Theoremfrege59a 38171 A kind of Aristotelian inference. Namely Felapton or Fesapo. Proposition 59 of [Frege1879] p. 51.

Note: in the Bauer-Meenfelberg translation published in van Heijenoort's collection From Frege to Goedel, this proof has the frege12 38107 incorrectly referenced where frege30 38126 is in the original. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)

 |-  (if- ( ph ,  ps ,  th )  ->  ( -. if-
 ( ph ,  ch ,  ta )  ->  -.  (
 ( ps  ->  ch )  /\  ( th  ->  ta )
 ) ) )
 
Theoremfrege60a 38172 Swap antecedents of ax-frege58a 38169. Proposition 60 of [Frege1879] p. 52. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 ( ( ps  ->  ( ch  ->  th )
 )  /\  ( ta  ->  ( et  ->  ze )
 ) )  ->  (if- ( ph ,  ch ,  et )  ->  (if- (
 ph ,  ps ,  ta )  -> if- ( ph ,  th ,  ze )
 ) ) )
 
Theoremfrege61a 38173 Lemma for frege65a 38177. Proposition 61 of [Frege1879] p. 52. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 (if- ( ph ,  ps ,  ch )  ->  th )  ->  ( ( ps  /\  ch )  ->  th ) )
 
Theoremfrege62a 38174 A kind of Aristotelian inference. This judgement replaces the mode of inference barbara 2563 when the minor premise has a particular context. Proposition 62 of [Frege1879] p. 52. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (if- ( ph ,  ps ,  th )  ->  ( ( ( ps  ->  ch )  /\  ( th  ->  ta )
 )  -> if- ( ph ,  ch ,  ta ) ) )
 
Theoremfrege63a 38175 Proposition 63 of [Frege1879] p. 52. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (if- ( ph ,  ps ,  th )  ->  ( et 
 ->  ( ( ( ps 
 ->  ch )  /\  ( th  ->  ta ) )  -> if- ( ph ,  ch ,  ta ) ) ) )
 
Theoremfrege64a 38176 Lemma for frege65a 38177. Proposition 64 of [Frege1879] p. 53. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 (if- ( ph ,  ps ,  ta )  -> if- ( si ,  ch ,  et ) )  ->  (
 ( ( ch  ->  th )  /\  ( et 
 ->  ze ) )  ->  (if- ( ph ,  ps ,  ta )  -> if- ( si ,  th ,  ze )
 ) ) )
 
Theoremfrege65a 38177 A kind of Aristotelian inference. This judgement replaces the mode of inference barbara 2563 when the minor premise has a general context. Proposition 65 of [Frege1879] p. 53. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 ( ( ps  ->  ch )  /\  ( ta 
 ->  et ) )  ->  ( ( ( ch 
 ->  th )  /\  ( et  ->  ze ) )  ->  (if- ( ph ,  ps ,  ta )  -> if- ( ph ,  th ,  ze )
 ) ) )
 
Theoremfrege66a 38178 Swap antecedents of frege65a 38177. Proposition 66 of [Frege1879] p. 54. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 ( ( ch  ->  th )  /\  ( et 
 ->  ze ) )  ->  ( ( ( ps 
 ->  ch )  /\  ( ta  ->  et ) ) 
 ->  (if- ( ph ,  ps ,  ta )  -> if- ( ph ,  th ,  ze ) ) ) )
 
Theoremfrege67a 38179 Lemma for frege68a 38180. Proposition 67 of [Frege1879] p. 54. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 ( ( ( ps 
 /\  ch )  <->  th )  ->  ( th  ->  ( ps  /\  ch ) ) )  ->  ( ( ( ps 
 /\  ch )  <->  th )  ->  ( th  -> if- ( ph ,  ps ,  ch ) ) ) )
 
Theoremfrege68a 38180 Combination of applying a definition and applying it to a specific instance. Proposition 68 of [Frege1879] p. 54. (Contributed by RP, 17-Apr-2020.) (Proof modification is discouraged.)
 |-  (
 ( ( ps  /\  ch )  <->  th )  ->  ( th  -> if- ( ph ,  ps ,  ch ) ) )
 
20.27.3.6  _Begriffsschrift_ Chapter II with equivalence of sets
 
Theoremaxfrege52c 38181 Justification for ax-frege52c 38182. (Contributed by RP, 24-Dec-2019.)
 |-  ( A  =  B  ->  (
 [. A  /  x ].
 ph  ->  [. B  /  x ].
 ph ) )
 
Axiomax-frege52c 38182 One side of dfsbcq 3437. Part of Axiom 52 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  ( A  =  B  ->  (
 [. A  /  x ].
 ph  ->  [. B  /  x ].
 ph ) )
 
Theoremfrege52b 38183 The case when the content of  x is identical with the content of  y and in which a proposition controlled by an element for which we substitute the content of  x is affirmed and the same proposition, this time where we substitute the content of  y, is denied does not take place. In  [ x  / 
z ] ph,  x can also occur in other than the argument ( z) places. Hence  x may still be contained in  [ y  / 
z ] ph. Part of Axiom 52 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( x  =  y  ->  ( [ x  /  z ] ph  ->  [ y  /  z ] ph )
 )
 
Theoremfrege53b 38184 Lemma for frege102 (via frege92 38249). Proposition 53 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( [ x  /  y ] ph  ->  ( x  =  z  ->  [ z  /  y ] ph )
 )
 
Theoremaxfrege54c 38185 Reflexive equality of classes. Identical to eqid 2622. Justification for ax-frege54c 38186. (Contributed by RP, 24-Dec-2019.)
 |-  A  =  A
 
Axiomax-frege54c 38186 Reflexive equality of sets (as classes). Part of Axiom 54 of [Frege1879] p. 50. Identical to eqid 2622. (Contributed by RP, 24-Dec-2019.) (New usage is discouraged.)
 |-  A  =  A
 
Theoremfrege54b 38187 Reflexive equality of sets. The content of  x is identical with the content of  x. Part of Axiom 54 of [Frege1879] p. 50. Slightly specialized version of eqid 2622. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  x  =  x
 
Theoremfrege54cor1b 38188 Reflexive equality. (Contributed by RP, 24-Dec-2019.)
 |-  [ x  /  y ] y  =  x
 
Theoremfrege55lem1b 38189* Necessary deduction regarding substitution of value in equality. (Contributed by RP, 24-Dec-2019.)
 |-  (
 ( ph  ->  [ x  /  y ] y  =  z )  ->  ( ph  ->  x  =  z ) )
 
Theoremfrege55lem2b 38190 Lemma for frege55b 38191. Core proof of Proposition 55 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( x  =  y  ->  [ y  /  z ]
 z  =  x )
 
Theoremfrege55b 38191 Lemma for frege57b 38193. Proposition 55 of [Frege1879] p. 50.

Note that eqtr2 2642 incorporates eqcom 2629 which is stronger than this proposition which is identical to equcomi 1944. Is is possible that Frege tricked himself into assuming what he was out to prove? (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)

 |-  ( x  =  y  ->  y  =  x )
 
Theoremfrege56b 38192 Lemma for frege57b 38193. Proposition 56 of [Frege1879] p. 50. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( x  =  y 
 ->  ( [ x  /  z ] ph  ->  [ y  /  z ] ph )
 )  ->  ( y  =  x  ->  ( [ x  /  z ] ph  ->  [ y  /  z ] ph ) ) )
 
Theoremfrege57b 38193 Analogue of frege57aid 38166. Proposition 57 of [Frege1879] p. 51. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( x  =  y  ->  ( [ y  /  z ] ph  ->  [ x  /  z ] ph )
 )
 
Theoremaxfrege58b 38194 If  A. x ph is affirmed,  [
y  /  x ] ph cannot be denied. Identical to stdpc4 2353. Justification for ax-frege58b 38195. (Contributed by RP, 28-Mar-2020.)
 |-  ( A. x ph  ->  [ y  /  x ] ph )
 
Axiomax-frege58b 38195 If  A. x ph is affirmed,  [
y  /  x ] ph cannot be denied. Identical to stdpc4 2353. Axiom 58 of [Frege1879] p. 51. (Contributed by RP, 28-Mar-2020.) (New usage is discouraged.)
 |-  ( A. x ph  ->  [ y  /  x ] ph )
 
Theoremfrege58bid 38196 If  A. x ph is affirmed,  ph cannot be denied. Identical to sp 2053. See ax-frege58b 38195 and frege58c 38215 for versions which more closely track the original. Axiom 58 of [Frege1879] p. 51. (Contributed by RP, 28-Mar-2020.) (Proof modification is discouraged.)
 |-  ( A. x ph  ->  ph )
 
Theoremfrege58bcor 38197 Lemma for frege59b 38198. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( A. x ( ph  ->  ps )  ->  ( [
 y  /  x ] ph  ->  [ y  /  x ] ps ) )
 
Theoremfrege59b 38198 A kind of Aristotelian inference. Namely Felapton or Fesapo. Proposition 59 of [Frege1879] p. 51.

Note: in the Bauer-Meenfelberg translation published in van Heijenoort's collection From Frege to Goedel, this proof has the frege12 38107 incorrectly referenced where frege30 38126 is in the original. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)

 |-  ( [ x  /  y ] ph  ->  ( -.  [ x  /  y ] ps  ->  -.  A. y (
 ph  ->  ps ) ) )
 
Theoremfrege60b 38199 Swap antecedents of ax-frege58b 38195. Proposition 60 of [Frege1879] p. 52. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  ( A. x ( ph  ->  ( ps  ->  ch )
 )  ->  ( [
 y  /  x ] ps  ->  ( [ y  /  x ] ph  ->  [ y  /  x ] ch ) ) )
 
Theoremfrege61b 38200 Lemma for frege65b 38204. Proposition 61 of [Frege1879] p. 52. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
 |-  (
 ( [ x  /  y ] ph  ->  ps )  ->  ( A. y ph  ->  ps ) )
    < Previous  Next >

Page List
Jump to page: Contents  1 1-100 2 101-200 3 201-300 4 301-400 5 401-500 6 501-600 7 601-700 8 701-800 9 801-900 10 901-1000 11 1001-1100 12 1101-1200 13 1201-1300 14 1301-1400 15 1401-1500 16 1501-1600 17 1601-1700 18 1701-1800 19 1801-1900 20 1901-2000 21 2001-2100 22 2101-2200 23 2201-2300 24 2301-2400 25 2401-2500 26 2501-2600 27 2601-2700 28 2701-2800 29 2801-2900 30 2901-3000 31 3001-3100 32 3101-3200 33 3201-3300 34 3301-3400 35 3401-3500 36 3501-3600 37 3601-3700 38 3701-3800 39 3801-3900 40 3901-4000 41 4001-4100 42 4101-4200 43 4201-4300 44 4301-4400 45 4401-4500 46 4501-4600 47 4601-4700 48 4701-4800 49 4801-4900 50 4901-5000 51 5001-5100 52 5101-5200 53 5201-5300 54 5301-5400 55 5401-5500 56 5501-5600 57 5601-5700 58 5701-5800 59 5801-5900 60 5901-6000 61 6001-6100 62 6101-6200 63 6201-6300 64 6301-6400 65 6401-6500 66 6501-6600 67 6601-6700 68 6701-6800 69 6801-6900 70 6901-7000 71 7001-7100 72 7101-7200 73 7201-7300 74 7301-7400 75 7401-7500 76 7501-7600 77 7601-7700 78 7701-7800 79 7801-7900 80 7901-8000 81 8001-8100 82 8101-8200 83 8201-8300 84 8301-8400 85 8401-8500 86 8501-8600 87 8601-8700 88 8701-8800 89 8801-8900 90 8901-9000 91 9001-9100 92 9101-9200 93 9201-9300 94 9301-9400 95 9401-9500 96 9501-9600 97 9601-9700 98 9701-9800 99 9801-9900 100 9901-10000 101 10001-10100 102 10101-10200 103 10201-10300 104 10301-10400 105 10401-10500 106 10501-10600 107 10601-10700 108 10701-10800 109 10801-10900 110 10901-11000 111 11001-11100 112 11101-11200 113 11201-11300 114 11301-11400 115 11401-11500 116 11501-11600 117 11601-11700 118 11701-11800 119 11801-11900 120 11901-12000 121 12001-12100 122 12101-12200 123 12201-12300 124 12301-12400 125 12401-12500 126 12501-12600 127 12601-12700 128 12701-12800 129 12801-12900 130 12901-13000 131 13001-13100 132 13101-13200 133 13201-13300 134 13301-13400 135 13401-13500 136 13501-13600 137 13601-13700 138 13701-13800 139 13801-13900 140 13901-14000 141 14001-14100 142 14101-14200 143 14201-14300 144 14301-14400 145 14401-14500 146 14501-14600 147 14601-14700 148 14701-14800 149 14801-14900 150 14901-15000 151 15001-15100 152 15101-15200 153 15201-15300 154 15301-15400 155 15401-15500 156 15501-15600 157 15601-15700 158 15701-15800 159 15801-15900 160 15901-16000 161 16001-16100 162 16101-16200 163 16201-16300 164 16301-16400 165 16401-16500 166 16501-16600 167 16601-16700 168 16701-16800 169 16801-16900 170 16901-17000 171 17001-17100 172 17101-17200 173 17201-17300 174 17301-17400 175 17401-17500 176 17501-17600 177 17601-17700 178 17701-17800 179 17801-17900 180 17901-18000 181 18001-18100 182 18101-18200 183 18201-18300 184 18301-18400 185 18401-18500 186 18501-18600 187 18601-18700 188 18701-18800 189 18801-18900 190 18901-19000 191 19001-19100 192 19101-19200 193 19201-19300 194 19301-19400 195 19401-19500 196 19501-19600 197 19601-19700 198 19701-19800 199 19801-19900 200 19901-20000 201 20001-20100 202 20101-20200 203 20201-20300 204 20301-20400 205 20401-20500 206 20501-20600 207 20601-20700 208 20701-20800 209 20801-20900 210 20901-21000 211 21001-21100 212 21101-21200 213 21201-21300 214 21301-21400 215 21401-21500 216 21501-21600 217 21601-21700 218 21701-21800 219 21801-21900 220 21901-22000 221 22001-22100 222 22101-22200 223 22201-22300 224 22301-22400 225 22401-22500 226 22501-22600 227 22601-22700 228 22701-22800 229 22801-22900 230 22901-23000 231 23001-23100 232 23101-23200 233 23201-23300 234 23301-23400 235 23401-23500 236 23501-23600 237 23601-23700 238 23701-23800 239 23801-23900 240 23901-24000 241 24001-24100 242 24101-24200 243 24201-24300 244 24301-24400 245 24401-24500 246 24501-24600 247 24601-24700 248 24701-24800 249 24801-24900 250 24901-25000 251 25001-25100 252 25101-25200 253 25201-25300 254 25301-25400 255 25401-25500 256 25501-25600 257 25601-25700 258 25701-25800 259 25801-25900 260 25901-26000 261 26001-26100 262 26101-26200 263 26201-26300 264 26301-26400 265 26401-26500 266 26501-26600 267 26601-26700 268 26701-26800 269 26801-26900 270 26901-27000 271 27001-27100 272 27101-27200 273 27201-27300 274 27301-27400 275 27401-27500 276 27501-27600 277 27601-27700 278 27701-27800 279 27801-27900 280 27901-28000 281 28001-28100 282 28101-28200 283 28201-28300 284 28301-28400 285 28401-28500 286 28501-28600 287 28601-28700 288 28701-28800 289 28801-28900 290 28901-29000 291 29001-29100 292 29101-29200 293 29201-29300 294 29301-29400 295 29401-29500 296 29501-29600 297 29601-29700 298 29701-29800 299 29801-29900 300 29901-30000 301 30001-30100 302 30101-30200 303 30201-30300 304 30301-30400 305 30401-30500 306 30501-30600 307 30601-30700 308 30701-30800 309 30801-30900 310 30901-31000 311 31001-31100 312 31101-31200 313 31201-31300 314 31301-31400 315 31401-31500 316 31501-31600 317 31601-31700 318 31701-31800 319 31801-31900 320 31901-32000 321 32001-32100 322 32101-32200 323 32201-32300 324 32301-32400 325 32401-32500 326 32501-32600 327 32601-32700 328 32701-32800 329 32801-32900 330 32901-33000 331 33001-33100 332 33101-33200 333 33201-33300 334 33301-33400 335 33401-33500 336 33501-33600 337 33601-33700 338 33701-33800 339 33801-33900 340 33901-34000 341 34001-34100 342 34101-34200 343 34201-34300 344 34301-34400 345 34401-34500 346 34501-34600 347 34601-34700 348 34701-34800 349 34801-34900 350 34901-35000 351 35001-35100 352 35101-35200 353 35201-35300 354 35301-35400 355 35401-35500 356 35501-35600 357 35601-35700 358 35701-35800 359 35801-35900 360 35901-36000 361 36001-36100 362 36101-36200 363 36201-36300 364 36301-36400 365 36401-36500 366 36501-36600 367 36601-36700 368 36701-36800 369 36801-36900 370 36901-37000 371 37001-37100 372 37101-37200 373 37201-37300 374 37301-37400 375 37401-37500 376 37501-37600 377 37601-37700 378 37701-37800 379 37801-37900 380 37901-38000 381 38001-38100 382 38101-38200 383 38201-38300 384 38301-38400 385 38401-38500 386 38501-38600 387 38601-38700 388 38701-38800 389 38801-38900 390 38901-39000 391 39001-39100 392 39101-39200 393 39201-39300 394 39301-39400 395 39401-39500 396 39501-39600 397 39601-39700 398 39701-39800 399 39801-39900 400 39901-40000 401 40001-40100 402 40101-40200 403 40201-40300 404 40301-40400 405 40401-40500 406 40501-40600 407 40601-40700 408 40701-40800 409 40801-40900 410 40901-41000 411 41001-41100 412 41101-41200 413 41201-41300 414 41301-41400 415 41401-41500 416 41501-41600 417 41601-41700 418 41701-41800 419 41801-41900 420 41901-42000 421 42001-42100 422 42101-42200 423 42201-42300 424 42301-42400 425 42401-42500 426 42501-42551
  Copyright terms: Public domain < Previous  Next >