graph_complected[T: TYPE]: THEORY
BEGIN
IMPORTING graph_conn_defs[T], graph_ops[T], graph_deg[T],
graph_inductions[T]
G,G1,G2: VAR graph[T]
v,v1,v2: VAR T
e: VAR doubleton[T]
%Consider moving below to graphs module.
two_vertices: LEMMA FORALL (v1,v2: T): edges(G)(e) AND e(v2) AND
vert(G) = dbl(v1, v2) IMPLIES e(v1)
sub_T: LEMMA FORALL (v: (vert(G))):
NOT empty?(vert(del_vert(G,v))) AND deg(v,G) = 0
IMPLIES NOT connected?(G)
rev_lem2 : LEMMA FORALL (v: (vert(G))):
connected?(G) AND
deg(v, G) = 1 IMPLIES
connected?(del_vert(G, v))
conn_lem2 : LEMMA FORALL (v: (vert(G))):
connected?(G) AND NOT isolated?(G) AND
deg(v, G) = 1 IMPLIES
(EXISTS (x: (vert(G))): deg(x, G) = 1
AND connected?(del_vert(G, x)))
del_rem_lem: LEMMA edges(G)(e) AND e(v)
IMPLIES del_vert(del_edge(G, e), v) = del_vert(G, v)
conn_lem3 : LEMMA connected?(G) AND NOT isolated?(G) AND
NOT (EXISTS (v: (vert(G))): deg(v, G) = 1)
IMPLIES
(EXISTS (e: (edges(G))): connected?(del_edge(G, e)))
BIG : LEMMA connected?(del_edge(G, e)) IMPLIES connected?(G)
conn_lem6 : LEMMA edges(G)(e) AND connected?(del_edge(G, e))
AND NOT isolated?(G) AND
NOT (EXISTS (v: (vert(G))): deg(v, G) = 1)
IMPLIES
connected?(G )
conn_eq_compl: LEMMA connected?(G) IFF
(IF isolated?(G) THEN singleton?(G)
ELSIF (EXISTS (v: (vert(G))): deg(v,G) = 1) THEN
(EXISTS (x: (vert(G))): deg(x,G) = 1 AND
connected?(del_vert(G,x)))
ELSE
(EXISTS (e: (edges(G))):
connected?(del_edge(G,e)))
ENDIF)
conn_del_vert: LEMMA (EXISTS (v: (vert(G))): deg(v,G) = 1 AND connected?(del_vert(G,v)))
IMPLIES connected?(G)
connected_not_empty: LEMMA connected?(G) IMPLIES NOT empty?(G)
connect_deg_0: LEMMA connected?(G) and vert(G)(v) and deg(v,G)= 0 IMPLIES G=singleton_graph(v)
END graph_complected
¤ Dauer der Verarbeitung: 0.17 Sekunden
(vorverarbeitet)
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