diff --git a/data_prep/R/polygon_slivers.R b/data_prep/R/polygon_slivers.R
index d485eb63..b92d52f5 100644
--- a/data_prep/R/polygon_slivers.R
+++ b/data_prep/R/polygon_slivers.R
@@ -1,68 +1,91 @@
 library(sf)
-library(data.table)
 library(dplyr)
-library(mapview)
 library(lwgeom)
-states1920 <- geobr::read_state(year = 1920)
-states1920 <- sf::st_read('C:/Users/user/Downloads/04_limite_estadual_1920/04-limite estadual 1920.shp')
 
-states1920 <- st_transform(states1920, crs = 4674)
-states1920 <- df
+# using planar geometry
+sf::sf_use_s2(FALSE)
 
-save(states1920, file = 'states1920.rda')
-saveRDS(states1920, file = 'states1920.rds')
+# load data
+states1920 <- geobr::read_state(year = 1920, simplified = F)
+plot(states1920)
 
-library(tlocoh) # http://tlocoh.r-forge.r-project.org/
-states1920_s <- tlocoh::clean_slivers(states1920_s)
-states1920_s <- as(states1920, 'Spatial')
+# test summarise with original data
+states1920$br <- 1
 
-sp.report <- clgeo_CollectionReport(states1920_s)
-sp.summary <- clgeo_SummaryReport(sp.report)
-sp.fixed <- clgeo_Clean(states1920_s, verbose = TRUE)
+states1920 |>
+  group_by(br) |>
+  summarise() |>
+  plot(col='gray90')
 
 
+# using make_valid and buffer
+states1920 |>
+  sf::st_make_valid() |>
+  sf::st_buffer(dist = 0) |>
+  group_by(br) |>
+  summarise() |>
+  plot(col='gray90')
 
 
-library(sf)
-library(dplyr)
-library(lwgeom)
-library(geobr)
+# using st_snap_to_grid
+states1920 |>
+  sf::st_make_valid() |>
+  st_transform(crs = 32722) |>
 
-# using planar geometry
-sf::sf_use_s2(FALSE)
+  lwgeom::st_snap_to_grid(size = 0.01) |>
+  group_by(br) |>
+  summarise() |>
+  plot(col='gray90')
 
 
-# load data
-states1920 <- geobr::read_state(year = 1920)
-plot(states1920)
+t <- dissolve_polygons(mysf=states1920, group_column='name_state')
+plot(t,col='gray90')
 
-# test summarise with original data
-states1920$br <- 1
 
+# using sfheaders
 states1920 |>
+  sf::st_make_valid() |>
   group_by(br) |>
   summarise() |>
+  sfheaders::sf_remove_holes() |>
   plot(col='gray90')
 
-
-# trying to fix with make_valid and buffer
-df1 |>
+# using nngeo
+states1920 |>
   sf::st_make_valid() |>
-  sf::st_buffer(dist = 0) |>
   group_by(br) |>
   summarise() |>
+  nngeo::st_remove_holes() |>
   plot(col='gray90')
 
+# using smoothr. This is the slowest solution
+area_thresh <- units::set_units(800, km^2)
 
-# trying to fix with st_snap_to_grid
-states1920 %>%
-  lwgeom::st_snap_to_grid(size = 0.0000001) %>%
+states1920 |>
+  sf::st_make_valid() |>
+  group_by(br) |>
+  summarise() |>
+  smoothr::fill_holes(threshold = area_thresh) |>
+  plot(col = "gray90")
+
+
+
+
+# using rmapshaper. It works by simplifying geometries, which I would consider
+# and unwanted side effect in this case
+
+states1920 |>
   sf::st_make_valid() |>
   group_by(br) |>
   summarise() |>
-  ungroup() |>
+  rmapshaper::ms_simplify() |>
   plot(col='gray90')
 
+
+
+
+
+
 # mother ship
 dissolve_polygons <- function(temp_sf, f){
 
@@ -71,7 +94,7 @@ dissolve_polygons <- function(temp_sf, f){
   dissolvefun <- function(grp){
 
     # c.1) subset region
-    temp_region <- subset(temp_sf, nome== grp )
+    temp_region <- subset(temp_sf, name_state== grp )
     #temp_region <- fgeos(temp_region)
     temp_region <- f(temp_region)
     return(temp_region)
@@ -79,13 +102,20 @@ dissolve_polygons <- function(temp_sf, f){
 
 
   # Apply sub-function
-  groups_sf <- pbapply::pblapply(X = unique(temp_sf$nome), FUN = dissolvefun )
+  groups_sf <- pbapply::pblapply(X = unique(temp_sf$name_state), FUN = dissolvefun )
 
   # rbind results
   groups_sf <- do.call('rbind', groups_sf)
   return(groups_sf)
 }
 
+##### sfheaders
+
+
+sfh2 <- dissolve_polygons(temp_sf = df, f = sfheaders::sf_remove_holes)
+sfh2$br <- 1
+sfh2 |> group_by(br) |> summarise() |> plot()
+
 
 ##### rgeos
 library(rgeos)
@@ -289,7 +319,16 @@ sss <- function(temp_region){ # temp_region = df[4,]
   return(poly)
 }
 
-sss2 <- dissolve_polygons(temp_sf = df, f = sss)
+sss2 <- dissolve_polygons(temp_sf = sta, f = sss)
 sss2$br <- 1
 #sss2 <- fix_topoly(sss2)
 sss2 |> group_by(br) |> summarise() |> plot()
+
+
+
+
+t <- dissolve_polygons(mysf = states1920, group_column = 'br')
+plot(t, col='gray90')
+head(t)
+
+
diff --git a/data_prep/R/support_fun.R b/data_prep/R/support_fun.R
index 6e39f577..4048dc23 100644
--- a/data_prep/R/support_fun.R
+++ b/data_prep/R/support_fun.R
@@ -304,7 +304,8 @@ to_multipolygon <- function(temp_sf){
 fix_topoly <- function(temp_sf){
 
   temp_sf <- sf::st_make_valid(temp_sf)
-  temp_sf <- temp_sf |> sf::st_buffer(0)
+  temp_sf <- sf::st_buffer(temp_sf, dist = 0)
+
   return(temp_sf)
 }
 
@@ -352,35 +353,13 @@ dissolve_polygons <- function(mysf, group_column){
     temp_region <- subset(mysf, get(group_column, mysf)== grp )
 
 
-    # c.2) create attribute with the number of points each polygon has
-    points_in_each_polygon = sapply(1:dim(temp_region)[1], function(i)
-      length(sf::st_coordinates(temp_region$geom[i])))
-
-    temp_region$points_in_each_polygon <- points_in_each_polygon
-    mypols <- subset(temp_region, points_in_each_polygon > 0)
-
-    # d) convert to sp
-    sf_regiona <- mypols |> as("Spatial")
-    sf_regiona <- rgeos::gBuffer(sf_regiona, byid=TRUE, width=0) # correct eventual topology issues
-
-    # c) dissolve borders to create country file
-    result <- maptools::unionSpatialPolygons(sf_regiona, rep(TRUE, nrow(sf_regiona@data))) # dissolve
-
-
-    # d) get rid of holes
-    outerRings = Filter(function(f){f@ringDir==1},result@polygons[[1]]@Polygons)
-    outerBounds = sp::SpatialPolygons(list(sp::Polygons(outerRings,ID=1)))
+    temp_region <- summarise(temp_region, .by = group_column)
+    # plot(temp_region)
 
-    # e) convert back to sf data
-    outerBounds <- st_as_sf(outerBounds)
-    outerBounds <- st_set_crs(outerBounds, st_crs(mysf))
-    st_crs(outerBounds) <- st_crs(mysf)
+    temp_region <- sfheaders::sf_remove_holes(temp_region)
+    temp_region <- fix_topoly(temp_region)
 
-    # retrieve code_region info and reorder columns
-    outerBounds <- dplyr::mutate(outerBounds, group_column = grp)
-    outerBounds <- dplyr::select(outerBounds, group_column, geometry)
-    names(outerBounds)[1] <- group_column
-    return(outerBounds)
+    return(temp_region)
   }
 
 
@@ -394,7 +373,7 @@ dissolve_polygons <- function(mysf, group_column){
 
 
 # # test
-# states <- geobr::read_state()
+# states <- geobr::read_state(year=2000)
 # a <- dissolve_polygons(states, group_column='code_region')
 # plot(a)
 
@@ -409,6 +388,7 @@ remove_state_repetition <- function(temp_sf){
     vars <- names(temp_sf)[-length(names(temp_sf))]
     temp_sf <- temp_sf |> group_by_at(vars) |> summarise()
     temp_sf <- temp_sf |> filter(!code_state=="0")
+    temp_sf <- unique(temp_sf)
     return(temp_sf)
 
   } else { return(temp_sf) }