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Mirrors > Home > MPE Home > Th. List > df-spths | Structured version Visualization version Unicode version |
Description: Define the set of all
simple paths (in an undirected graph).
According to Wikipedia ("Path (graph theory)", https://en.wikipedia.org/wiki/Path_(graph_theory), 3-Oct-2017): "A path is a trail in which all vertices (except possibly the first and last) are distinct. ... use the term simple path to refer to a path which contains no repeated vertices." Therefore, a simple path can be represented by an injective mapping f from { 1 , ... , n } and an injective mapping p from { 0 , ... , n }, where f enumerates the (indices of the) different edges, and p enumerates the vertices. So the simple path is also represented by the following sequence: p(0) e(f(1)) p(1) e(f(2)) ... p(n-1) e(f(n)) p(n). (Contributed by Alexander van der Vekens, 20-Oct-2017.) (Revised by AV, 9-Jan-2021.) |
Ref | Expression |
---|---|
df-spths | SPaths Trails |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | cspths 26609 | . 2 SPaths | |
2 | vg | . . 3 | |
3 | cvv 3200 | . . 3 | |
4 | vf | . . . . . . 7 | |
5 | 4 | cv 1482 | . . . . . 6 |
6 | vp | . . . . . . 7 | |
7 | 6 | cv 1482 | . . . . . 6 |
8 | 2 | cv 1482 | . . . . . . 7 |
9 | ctrls 26587 | . . . . . . 7 Trails | |
10 | 8, 9 | cfv 5888 | . . . . . 6 Trails |
11 | 5, 7, 10 | wbr 4653 | . . . . 5 Trails |
12 | 7 | ccnv 5113 | . . . . . 6 |
13 | 12 | wfun 5882 | . . . . 5 |
14 | 11, 13 | wa 384 | . . . 4 Trails |
15 | 14, 4, 6 | copab 4712 | . . 3 Trails |
16 | 2, 3, 15 | cmpt 4729 | . 2 Trails |
17 | 1, 16 | wceq 1483 | 1 SPaths Trails |
Colors of variables: wff setvar class |
This definition is referenced by: spthsfval 26618 |
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