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References to 'empty set'
1. absorbing element by pahio
2. affine geometry by CWoo
3. algebraic sets and polynomial ideals by mathcam
4. alternative definitions of countable by CWoo
5. ambiguous grammar by CWoo
6. arrows relation by Henry
7. axiom of choice by GrafZahl
8. axiom of foundation by Henry
9. axiom schema of separation by Sabean
10. barycentric subdivision by CWoo
11. basis by mathcam
12. Bolyai-Gerwien theorem by CWoo
13. bounded complete by CWoo
14. Bourbaki, Nicolas by Daume
15. Burnside ring by joking
16. Cartesian product by djao
17. categorical pullback by CWoo
18. clopen subset by mathcam
19. closure map by CWoo
20. complete lattice by yark
21. complete semilattice by CWoo
22. concatenation by CWoo
23. concepts in set theory by matte
24. consequence operator by rspuzio
25. constructing well ordered sets by CWoo
26. construction of outer measures by gel
27. convex subgroup by CWoo
28. countable complement topology by mathcam
29. criteria for a poset to be a complete lattice by CWoo
30. derived Boolean operations by CWoo
31. discrete category by CWoo
32. disjoint by djao
33. empty sum by pahio
34. equivalent definitions of analytic sets by gel
35. example of Boolean algebras by CWoo
36. example of function not Lebesgue Measurable with measurable level sets by cvalente
37. example of universe by rspuzio
38. examples of countable sets by CWoo
39. examples of initial objects and terminal objects and zero objects by AxelBoldt
40. examples of rings by matte
41. exponential object by CWoo
42. face of a convex set by CWoo
43. face of a convex set, alternative definition of by mps
44. fibre by mathcam
45. filter basis by rspuzio
46. finite complement topology by mathcam
47. finitely generated module by Thomas Heye
48. free Boolean algebra by CWoo
49. free group by yark
50. from Hilbert's tenth problem to G\"{o}del's trichotomy by gribskoff
51. frugal number by PrimeFan
52. FS iterated forcing preserves chain condition by Henry
53. functions from empty set by rspuzio
54. geometric lattice by CWoo
55. Hausdorff's maximum principle by CWoo
56. homogeneous group by whm22
57. homomorphism between algebraic systems by CWoo
58. induction by Daume
59. infinite by yark
60. intersection of sphere and plane by pahio
61. interval by PrimeFan
62. language by mps
63. limit of sequence of sets by CWoo
64. limiting cone by CWoo
65. linear equation by rmilson
66. linear erasing by CWoo
67. locale by CWoo
68. long exact sequence (of homology groups) by mathcam
69. matching by Mathprof
70. matroid by mps
71. maximal bipartite matching algorithm by mathcam
72. motivation for von Neumann ordinals by yark
73. natural number by djao
74. oriented cobordism by mathcam
75. orthonormal set by yark
76. outer measure by mathcam
77. parabolic subgroup by bwebste
78. paved space by gel
79. predictable process by gel
80. preorder as a category by CWoo
81. product of non-empty set of non-empty sets is non-empty by CWoo
82. proof of alternative characterization of filter by rspuzio
83. proof of Carath\'eodory's lemma by gel
84. proof of every filter is contained in an ultrafilter (alternate proof) by brunoloff
85. properties of direct product by CWoo
86. properties of well-ordered sets by GrafZahl
87. relative interior by CWoo
88. ring of sets by CWoo
89. Russell's theory of types by Aatu
90. scattered space by CWoo
91. self-similar fractals by paolini
92. set by Mathprof
93. signature by CWoo
94. simplicial category by mhale
95. Smarandache n-structure by jonnathan
96. span by mathwizard
97. spectrum is a non-empty compact set by asteroid
98. sphere (metric space) by rspuzio
99. strict betweenness relation by Mathprof
100. subgroup by Daume
101. subset by Wkbj79
102. superset by yark
103. Tarski-Knaster theorem by kompik
104. Tutte theorem by scineram
105. Tychonoff's theorem implies AC by CWoo
106. uniform space by mps
107. union by rm50
108. vacuous by matte
109. variety of groups by yark
110. von Neumann ordinal by Henry